Future Energy Sources 2.1 Battery Electric Vehicles

Lets face it the internal combustion engine commited murder and the battery car commited suicide.

Both should marry to avoid murder and suicide. Hybrid electric vehicle using an efficient engine running at optimum speed and load for best fuel efficiency and replacing batteries used normally for back up which normally make the vehicles haevy and sluggish is the solution.

rsb

The hybrid is the bastad off spring, that is the worst of both worlds, because you are dragging around the weight of the batteries when using the engine and the weight of the engine plus batteries when using the motors. No one wins this way. Oh yes and the gas/petrol when using either motor or engine as well and in the event of a crash it is a lot less safe. Hybrids should be banned!

And should all paddle steamers have been banned for inefficiency?

What about Bi-planes?

Or the first "Horseless carriages"?

To get progress, we must look at all possibilities, and experiment with them to find a workable solution.

Personally, I think that the use of the correct types (yes, in plural) of hybrid will give savings, not just in fuel used but in the weight of the vehicle.

Look at the new hybrid trucks, using much smaller engines which operate at near constant speed, and are therefore much more economical. The power produced is stored in hydraulic systems, also giving faster acceleration without any significant increase in weight over the "normal" unit. These are only suited to stop/start driving at present, but as this is where the larger engines are much less efficient it is the best use of this technology.

Of course bad hybrids are worse than either parent; this applies whatever type of technology you are using, not just transportation. Clearly, a hybrid can provide a portion of the advantages and a portion of the disadvantages of both; if you take the trouble to match this to the requirements there can be an overall benefit.

In automotive applications, the onboard engine can save in distribution costs compared with charging the batteries over the grid. The onboard battery can recover energy that would otherwise be wasted during braking; it can also provide some of the peak load, so the engine can be designed for peak efficiencies at the lower power output level that is required most of the time. At present the extra weight from the batteries exceeds the weight savings in the engine, but there are still advantages.

At the moment, the principle downside is the additional costs of manufacture and maintenance that seem to be a long way from being recoverable. It could be that this is merely a result of the small numbers that have been made to date.

Hybrid vehicles should become valuable; for some applications, they already are. In my mind, the question is when (rather than if) they will become viable for general use. (Hopefully, this is not like Gallium Arsenide semiconductors)

Fyz

The ideal way would be to have a super efficient solar cells on the roof and a small DC generator that charges the batteries that are now very light weight and super power dense, you have two sets of batties one lot in use the other charging or waiting to be used. Never need to travel long distances, and have the over all weight of vehicle plus max load weigh no more than two feathers. Have a drag factor of zero. Always go down hill where ever you need to get to and also when you need to return home.

The problem with trying to use solar panels mounted on the car is the efficiency of the panels and the size of the car. At absolute best you can only get about 400 watts per square meter from solar panels and you would be lucky to fit 2 m² of solar panels on a car. Even the smallest internal combustion driven cars have engines that produce 40 Kw and that means you need to have a charging to use time ratio of at least 50 to 1. Given that you can only charge for half a day that means you could only use the car for less than 15 minutes a day.

Unfortunately the energy in the sunlight that falls on the earth is limited to a maximum of about 1 Kwm^-2. That means that to collect the sort of energy that a car uses you need to use solar panels that are considerably larger than the car.

The concept of having an autonomous, self charging car is very desirable but is unfortunately an impossibility due to the energy density of sunlight and the space and time available.

Have you never heard of sarcasm? Scepticism? A little mockery?

Solar cells, cheaply printed on film

Covering every roof possible

Would be desirable

But I suppose this is the wrong thread, for solar

My car runs 20' in the morning, and 20' in the evening.

I drive 35km a day.

It would be great to do this electric.

Taken into account the visits to my parents once a month , I need an activity radius of 200km.

What prohibits the use of other fuels? Action radius.

With a full loaded tank I can drive between 800 and 1000km (depending on the speed and airco use)

Take out all the unneccesary stuff, make a carbon fiber car and give it an action radius of 250km. Almost 90% of the cars could be replaced with it.

A kg of carburant contains approx 40 MJ. A KWH is 3.6 MJ.

A car ICE an efficiency of approx 25% over the whole range. This means that weeed to store 3 KWH to replace a kg of carburant.

To my calculations, a battery pack of the same wheight of the engine and loaded tank (use engine wheels) must be able to do the trick. (200 to 250 km action radius)

Charging can be done by adding PV cells to the roof of your house and in wintertime though the net.

Why isn't it there, promoted by the goverment? They need to get paid, they need the money from the tax.

It took years to get the local goverment to accept bio fuels to be used. Now they need to accept electicity, that can be self generated. (a stove with stirling generator, wait, we can't go to bed yet, the car is not yet fully loaded)

I imagine you join major roads for the longer distances, and that these are quite busy. If we organised to load light-weight short-range electrical vehicles onto transporters for the longer distances, and transferred between transporters at strategically-placed junctions...

The basic technologies already exist. If we are worried about the driver of the transporters*, it shouldn't be long before reliable automated versions become practical - particularly if we give them absolute priority (like trams).

*Do we really prefer to trust our abilities to avoid the vagaries of multiple other drivers on overcrowded roads rather than to fewer other drivers on roads that are less densely packed? That suggests the illusion of 'being in control' is awfully powerful.

Life after ?? - no energy, no distances, all skin and bones, and downhill all the way.

Fyz

Let's separate the problem into smaller pieces and target special uses (special markets) for electric cars that may justify their limitations. Maybe Corporation fleet cars, very urban areas, where space is limited, pollution high, and high performance designer cars that high-enders want. If we can displace just 10% of the existing oil usage we could resolve a lot of world tension.
See additional links:
http://www.altairnano.com/ Jay Leno looks under the hood.

http://www.myfoxla.com/myfox/pages/Home/Detail;jsessionid=301FF555AE9112686BCDBDA28647F765?contentId=2399724&version=1&locale=EN-US&layoutCode=VSTY&pageId=1.1.1

I commend your attempt at informing the public about the advantages and disadvantages of BEV vehicles. I do think you arei n error on several key points, and that the future is far better than you portray.

First, the pollution issue. Emissions from electric vehicles are not just displaced emissions, and the inefficiencies of electric power production do not come anywhere close to the inefficiencies of an internal combustion engine.

The best internal combustion engine, finely tuned and running perfectly is only 12% to 15% efficient. An electric propulsion system has much higher efficiencies. Motors can be as high as 95% efficient, controllers/inverters as high as 92% efficient, and batteries 80% to 85% efficient. Then you can recover as much as 3% to 5% of that energy with even poorly designed regenerative braking.

Power plants are also very efficient. They operate anywhere from 60% efficient to 85% efficient. Transmission and distribution losses are only about 8% of the total. All of this takes into account most power plants run all night even though the electricity generated is not all used. It literally goes to waste, since it is too expensive to cycle the plants on and off. That means that literally millions of BEV vehicles can be powered without increasing emissions already produced.

Further, it is far easier to control a single smokestack than it is to control millions of tailpipes. The emissions from power plants are generally not located in lsarge population centers but rather on the outskirts of those centers. Finally, smokestacks emit their pollutants at least 100 feet above the ground, whereas internal combustion engine vehicles emit at ground level, in the densely populated centers and those pollutants cannot disperse they way they do when coming out of smokestacks.

Independent studies by the Union of Concerned Scientists and others have proven time and time again that emissions from electric vehicles are far less than from internal combustion engines. The Electric Power Research Institute had several studies done in the 1990's that proved that electric vehicles were 98% cleaner than internal combustion engine vehicles even when the generation, transmission and distribution was taken into account. These studies were based on a fuel mix of 55% coal, 4% petroleum, 18% natural gas, and the rest nuclear, hydro, wind and other. Since those studies were done, our generation mix has become cleaner and smokestack emissions have been reduced.

As for batteries, there are a lot of possibilities out there that are as yet untapped. Think of the periodic table of elements. There are over 103 distinct and different elements, not counting man made elements. Add in things such as temperature, pressure, gravity and other variants and then calculate how many possible variations there are. It is something on the order of 110 factorial. In other words many milluions of lifetimes to try them all.

The poinyt that I make here is that we have but scratched the surface of battery development. Aluminum Sulfur, Nickel Hydrogen, Lithium Polymer, Zinc Air, Zinc Bromine, Silver Hydrogen, and the list goes on and on. The possibilities are nearly endless. Even the lithium ion batteries have many different aspects, ranging from nano engineering to phospatized electrodes, to material utilization rates, all effecting and increasing the possibilities. Look as Altair Nano, Valence Technologies and 123 as examples.

In 1994 I managed the development of a sedan with the interior room of a Ford Taurus, that went 377 miles on a single charge using nickel metal hydride batteries. This battery technology is inferior to what is possible today.

In a short time, I expect BEV's to be mass produced and sold at a competitive price to internal combustion engine vehicles. The only thing holding up that production is investment dollars. And soon, even that will be resolved!

I could literally write a book on why the successful commercialization of BEV's is imminant and inevitable. If you want more information or have specific questions please feel free to contact me directly.

JHOGA72225@AOL.COM

Jim Hogarth

E4 EVE

Jim,

You make a number of excellent points. A few comments of my own,

I've been driving all-electric since 1998. I don't agree with the premise in the original blog entry that charging is a big problem compared to filling up for several reasons and, in fact, my experience has shown that charging my EV - from a practical day to day point of view - takes about the same amount of time as everyone else spends fueling their ICE vehicles.

First, we EV drivers don't typically plug in and then stand around waiting for the batteries to charge. We plug in when we're not driving. The time it takes to plug in and unplug (10-15 seconds) for every 350 miles traveled adds up to about the same time or less than it takes an ICE driver to fill up their tank. Only we're not dripping gas on our shoes, sending gas vapors into the atmosphere, and breathing the gas fumes in the process.

Secondly, the EVs I've owned have had "distance-to-empty" mileage varying from 30 to 60 miles. The average driver travels about 40 miles per day. True, some people travel farther and some less, but that's average. The Ford Ranger truck I leased for 4 years with NiMH batteries went 60,000 miles over that period. That's 15,000 miles per year and 41 miles per day.

What I've learned over the last 9 years of driving electric has been life-altering. For example I was surprised to find how practical it really is to drive electric. It has taught me that, with a minute of investment in planning trips more thoughtfully I can not only save miles traveled but, perhaps most importantly, 20-30 times more time than I invested in planning my trips. So, not only do I make 40 miles per day work on a practical basis but I'm wasting less time in the process. This helped me finally "get" what my college engineering professor used to always tell us "When all else fails, think!" A minute invested reducing wasted time by 20-30 times is an excellent return on investment.

I did see two things about your post I hoped you would clarify -

1) I didn't see mentioned Firefly energy. They're in partnership with Catepillar and Husquevarna (SP?) to provide advanced lead-acid batteries with the equal to or better performance in all respects to the new lithium-ion technologies but at a fraction of the price.

2) The electric power generation sector is not as efficient as you stated. A commonly accepted figure is 1/3 energy delivered from source to end use.

That last comment, however, does not negate the fact that many detailed studies by goverment organizations over the years have found that, overall efficiency-wise, an EV is more efficient and less polluting than its ICE counterparts. Most studies make a small exception for certain pollutants being greater in areas with mostly coal-fired plants.

Also, as you probably know, the technology for fast charging an EV (in about the time it takes to fill up an ICE vehicle) that can go the same distance as an ICE vehicle is here and now. It will take economy of scale and infrastructure improvements to make it a reality but this is all possible now and would be an excellent public investment.

Locally produced electricity, from more efficient biomass and other renewable sources, can greatly reduce the waste we have as a nation in our two biggest sectors of waste - transportation and electric power generation. That's how I've powered my EV for the last six years and achieved a return on investment from my distributed generation system! Changes such as I've made on a larger scale, in concert with EVs used by most average drivers would improve the environment, the economy, national security and help guarantee a more sustainable future for our country.

Hi JHOGA,

Welcome to CR4, I hope you find being involved as rewarding as I. I do not know if you are aware of it but this thread is one in a series that we are using to discuss any technology that may help reduce our dependence on fossil fuels. You can find a list of the technologies that I intend to start discussions on plus links to discussions that have already taken place on the blog index page. If you have a technology you feel warrants discussion and is not already on the list pleas follow this link to send me a message and I will happily add it to the list. This forum is for discussion and I am often limited on what I can find on the internet for background research so there may be discrepancies it the introduction. If there is something that is incorrect pleas don't hesitate to correct it an supply links to more update and detailed information.

"Power plants are also very efficient. They operate anywhere from 60% efficient to 85% efficient. Transmission and distribution losses are only about 8% of the total."

I think you will find that the 60% to 85% is the efficiency of the generator and dose not take into account the thermal efficiency you end up with an overall efficiency of around 33%. You then need to take into account the losses in transmission, rectifier and charger, battery and electric motor. Together that all adds up like this

• Generating Thermal Efficiency = 33%
• Transmission Line Efficiency 92%
• Charger Efficiency = 92%
• Battery Recovery Efficiency = 80%
• Electric Motor Efficiency = 90%
• Overall Efficiency = 20%

So that gives you an overall efficiency of around 20%. Internal Combustions Engines ICE are also somewhat more efficient than you claim and I believe you will find that they fall within the range of 20% to 37% so that makes BEV at best the same and probably worse then ICE. If you now look at the profile of the fuels used to generate the electricity as in this chart

You will see that almost half of the energy is generated by burning coal which generates considerably more pollution than gasoline. Put it all together and it means that electric vehicles actually create more green house gasses and pollute the atmosphere more than internal combustion engines. If you move to hydrogen and fuel cells it is even worse as the production of hydrogen is terribly inefficient.

"As for batteries, there are a lot of possibilities out there that are as yet untapped. Think of the periodic table of elements. There are over 103 distinct and different elements, not counting man made elements. Add in things such as temperature, pressure, gravity and other variants and then calculate how many possible variations there are. It is something on the order of 110 factorial. In other words many milluions of lifetimes to try them all."

All up there are 117 know elements although there is a gap at element 117 which would tend to indicate that there are at least 118 elements. However not all of these are stable and there are only 90 elements that you will find occurring naturally

You can't just combine any two elements from the periodic table and make them work as a battery. If you look you will see that the periodic table is divided into groups. These groups contain elements that have similar chemical properties and this means you can't just pick any two elements and make a useful battery from them. Ultimately if you are trying to construct a useful battery you are severely limited by which elements can be used and which elements they can be combined with. Put simply the workable combination and chemistries are severely limited and nothing even remotely close to the 110! you suggest.

I response to the guest's post #5

I've been driving all-electric since 1998. I don't agree with the premise in the original blog entry that charging is a big problem compared to filling up for several reasons and, in fact, my experience has shown that charging my EV - from a practical day to day point of view - takes about the same amount of time as everyone else spends fueling their ICE vehicles.

This is true and can actually be an advantage but the problem is you can't get the vehicle recharged from flat to fully charged in the time that it takes to fill a tank with a liquid fuel.

Secondly, the EVs I've owned have had "distance-to-empty" mileage varying from 30 to 60 miles. The average driver travels about 40 miles per day. True, some people travel farther and some less, but that's average.

That might be an acceptable range in Europe or North America but in places like Australia it make the vehicle completely useless. To give you some sort of idea while I was working as a field engineer for a computer company a round trip from home to the office was nearly 80Km (50 Miles) and that's before you start needing to travel to customers.

Another problem is long distance travel and once outside the major population centers as places you can refuel are scarce. If you wish to travel off the main roads (there are bugger all main roads in Australia) you will need a range of at least 200 Km. This makes a vehicle that can't get at least 200 Km and be refueled in minutes completely useless to anybody that needs to travel outside the major population centers.

Also, as you probably know, the technology for fast charging an EV (in about the time it takes to fill up an ICE vehicle) that can go the same distance as an ICE vehicle is here and now. It will take economy of scale and infrastructure improvements to make it a reality but this is all possible now and would be an excellent public investment.

I was under the impression that the technology you are speaking of was using super capacitors and was not yet fully developed. The problem with charging most rechargeable batteries too quickly is that you can damage them and seriously reduce their life expectancy. LiIon batteries are the worst and are prone to explosion and starting fires if charged incorrectly. If this technology is actually already available I would be interested to know more and any links to information on the technology would be appreciated.

Having said all that BEV do have advantages and their ability to recapture a percentage of the energy expended when accelerating makes them particularly suitable for stop start city use. I do believe BEV have a large part to play in the future of personal and public transport but we need to be sure that we are using ecologically sound electricity generation to power them. Currently at best BEV are just moving the pollution and in places like Australia where nearly all the electricity is generated from burning cola you may actually be creating more with an electric vehicle. The out of sight out of mind attitude of many of our politicians is a serious problem and there is a risk of just moving the pollution and then ignoring the problem as a whole.

There was talk some years ago about the development of a dual electrolyte battery for use in BEV, that could be recharged by simply draining the depleted electrolytes and replacing them with fresh electrolytes. This would be a huge step in the right direction and would make recharging similar to the current refueling process but I have been unable to find anything current on the status of the development of such a system.

In all of these comments I see no mention of solar energy. A portion of my buddy's roof (1000 sq.ft.) is covered with solar panels. Not only do they generate 15 kW but they generate hot water as well. He can easily recharge any electric vehicle including his electric lawnmower.

This system has been in place for eight years and has produced enough resale electricity (to the electrical co-op) to pay for the mower and the golf cart in which he cruises around the neighborhood. The hot water is stored in two insulated 150 gallon tanks and even in this snowy northern California winter with his less than energy conservative wife and four daughters LOL he claims to have never run out of hot water. He does have an electrical tankless HWH as a backup and truthfully I don't know if it has ever been used. We have checked it occassionally and it operates well in the manual test mode.

The hot water is also used to de-ice the solar panels and plans are in place to develop another HW storage system and use it to heat the house and de-ice the driveway. He has bid on an old surplus stainless steel insulated railway wine tank car. It holds 8,000 gallons and another set of solar panels will be used to charge it with hot water and produce the pumping electricity. His current solar panel system will produce an unregulated 180 deg. F water but it is currently regulated at 120 deg. F. He plans to let the 8,000 gallon system reach the maximum temperature the solar panels will provide.

I'm converting to solar this summer and plan to duplicate his system except I won't be deicing my driveway. The cost is tax deductable and rebate programs will cover most of the cost of installation. I also want to get an EV for my daily 14 mile commute.

After watching my buddy's success with his system and reducing our expenses (my daughters are now married LOL) I think solar power will enhance our lives measureably.

The new nano phosphate lithium ion batteries patented and manufactured by A123 can be recharged in 5 minutes, and could reduce the weight of the batteries in a Toyota Prius by 80 percent, while maintaining the same power.They can be recharged up to 2000 times.

This appears to be a breakthru on technology insofar as safety,power density, fast charge, and environmental concerns, containing no environmentally hazardous chemicals.

The problem now is getting GM, which is partnered with A123 to get off their duff and start making the cars.They should be inherently cheaper to produce than an ICE, and virtually maintenance free, judgeing by my experience with battery powered industrial fork lifts.(I am speaking of Pluggable Hybrids).

HTRN

This is certainly the sort of technical breakthrough that could give the battery electric vehicle the edge it needs to get going. What needs to be done by all and sundry is to put GM under as much pressure as possible to force them to develop this technology to mass production level and implement it in as many vehicles as possible.

It's a critical and important development and if GM decide to sit on it we should all show GM how such behavior is totally and absolutely unacceptable.

I wonder it Tesla Motors will be able to use them in their roadster?

I think this must depend on whether GM have learned from the trouncing they underwent when they decided that "steady as you go" with petrol guzzlers would keep them at the top of the market when overseas competitors were coming in with small, high-quality cars.

Unfortunately I have my doubts, as the habit of providing "replacement" models that are a few percent larger than their predecessors persists.

Fyz

In my opinion, we are going towards a different direction, say, we do not need to choose a fuel and we might fix ourselves in the real objective: to displace a body from a place to other.

Have you ever listen about connected universes?

I think that the solution would be to find gates between paralel universes.

Example: you leave a place in one universe , walk in the other and return to the original universe.

For one observer in the original universe no time would be spent as time change would be instantaneous.

It is a complicate idea? Well, for those in the XV century, it was completely unbelivable a portable pnone to exist.

So, the solution would be to study mathematics and phisics, in order to find such boundary gates.

Kind regards

Car manufacturers have been developing commercially viable hybrids with tax dollars for decades. In 1969, GM even built a hybrid electric with a battery that charges from a built-in Stirling engine! It was very fuel efficient and I can't think of any legitimate reason why it wasn't mass produced during the 70's oil crisis.

http://econogics.com/ev/stirlec1.jpg

http://www.evworld.com/blogs/index.cfm?page=blogentry&authorid=46&blogid=113&archive=1

A good point was made that EVs are more efficient because power plants are far more efficient then ICEs and because EVs can recharge over night on grid power that would otherwise go to waste. Plus, power plants disperse pollution much better than ICEs. A counterpoint was made that only the electric generators of power plants are very efficient but the total thermal efficiency of power plants is actually about equal to or slightly better than ICEs which makes the charging of EVs equal to or slightly less efficient that ICEs. Plus, burning the fuel in power plants rather then in ICEs only shifts the pollution out of sight and out of mind.

At this point, the ICE is winning by a neck. However, if we consider the efficiency by which fuel would be transported in bulk from oil refineries to a few hundred remote power plants around the country to the efficiency by which fuel is currently being transported from refineries to thousands of leaky gas stations and millions of sloppy drivers, leaky gas tanks, tons of vapor waste, it just seems to me that EVs end up winning head and shoulders overs ICEs. Plus, given the choice of breathing MTBE or fresh air, I'd take the fresh air any day.

Hi Harbinger,

You have raised some interesting points. The auto and oil industries are probably the most stagnant industries that have ever existed when it comes to innovative engineering. They love to spend hundreds of millions of dollars each year on what ends up being cosmetic changes that offer absolutely no real benefit what so ever. However, spending a billion dollars on another drilling and processing rig gats approved by management without batting an eye.

If research was funded to the order that the oil industry spend on a single oil rig of the car industry spent on a single years cosmetic changes then maybe we would see the sort of advances that the electronics industry has seen.

If the automotive industry had advanced at the rate the electronics industry had we would all have vehicle that could travel at the speed of light, could fit in your pocket yet have a three bedroom house inside, would only need and AA better to run and cost 99 cents to buy brand new.

Last year, when the price of petrol in Australia started to go through the roof I did a comparison of the cost of petrol and electricity on a straight per unit of energy basis. It turned out that at that time when petrol cost around a $1.19 a liter and electricity $0.13 per KwH that they worked out relatively the same price per Kj. This however did not take into account things like regenerative braking, the efficiency of the engines, transmissions, etcetera or off peak electricity tariffs. If you wish to do the comparison yourself for your local prices a liter of petrol contains about 34.831 Mj of energy.

"If the automotive industry had advanced at the rate the electronics industry had we would all have vehicle that could travel at the speed of light, could fit in your pocket yet have a three bedroom house inside, would only need and AA better to run and cost 99 cents to buy brand new."

Much quoted, but quite untrue. If you take human achievement as the reference, the most we can do even for short periods is 25-mph. A car is vastly more rapid. Yet, to date, no computer can perform the full gamut of processing tasks that are a human's birthright. (By way of comparison, the original AT computers were said to have a processing power similar to the average slug's. That was flattering to the AT computer, because it didn't include the intelligence that was built into the slug's sensors.)

Another way of looking at this: the individual transistor components of the processor have got a lot smaller, and the processing speed has improved, but the PC box is typically larger than the 1970's AppleII, and consumes more power. And just look at the results of all that money apparently spent developing the software.

If the automotive industry had progressed like the computer part of the semiconductor industry, your car would be great at going around in small circles, and stall and turn blue whenever you wanted to perform a manoeuvre it wasn't anticipating

"Another way of looking at this: the individual transistor components of the processor have got a lot smaller, and the processing speed has improved, but the PC box is typically larger than the 1970's AppleII, and consumes more power."

I must vehemently disagree with your statement. The first computer that I ever used was and IBM 360/20 and it now resides in a museum. It consisted of a room full of equipment, had a massive 8 KB of core memory and consumed about 7.2 Kw of power.

Compare that to the notebook that I am currently using to compile this message. It has 1,070,741 KB of memory, fits on my lap and consumes a massive 70 W of power so it runs all the time.

Lets put the two together.

• Memory 8 KB to 1 GB = 13,000,000% improvement
• Cost $250,000 to $1,500 = 99.4% reduction
• Energy Consumption 7.2 Kw to 70 w = 99% reduction

So lets look at the car I had at the time and apply the same sort of improvements.

• Engine Power 52 Kw x 13,000,000% improvement = 6.7 Gw
• Cost $1,500 x 99.4% reduction = $9
• Fuel consumption 12L/100Km x 99% reduction = 120 ml/100Km

When you do the comparison that way the auto industry has grossly underperformed when compared with the computer industry.

I agree it is an unfair comparison but it dose prove my point that if the auto industry had shown the same improvements that the computer industry did then the cars we are currently seeing would be dramatically different.

I'll add a few of my own comments:

Size - this reduces until the population of users will not buy it any more: with cars, the US has generally stopped at "big bricks", and in the UK we have limited success with the 2-seat "Smart" range. Personally, I think those in between will prevail.

With computers, they could be smaller,too, but lose efficiency as the number of keys/size of screen reduce (Psion Organiser?)

Power - both industries keep adding power, but there are signs that improvements in reliability would be preferred............but more power is easier, so...

Price - there is a limit to how far price can drop, as the physical size dictates the amount of raw materials required. I have no doubt that cars could be made much smaller and cheaper, but would they be as useful?

Hi Masu

To play devils advocate:- I think both you and guest have good cases, but in terms of progress vs limits I would tend to come down on the side of guest. There are three areas in which I think the comparison should be made:

First, you are looking at computing progress through the immature stages of the technology. I might say that it is still marginal whether we can rely on working computers to perform the required function without any preliminary user fiddling. Of course, what I am complaining about here is software, or the weakest link - but that is what characterises the effectiveness of a technology. I expect to be able to get into my car and go from A to B (or C) whenever I please. My computer still makes life difficult from time to time if I want to do "go where I please".

Second, the way you are measuring progress. If you measure versus how close the system is to theoretical limits, the measures you are using for computing show it to be orders of magnitude away from what is possible within the same technology. Car engines run at 30% fuel usage efficiency, with theoretical limits that are probably in the region of 50% within the metal-engine technology.

The third point, and the one made by guest, is that you should be comparing what the technology has made possible compared with what is possible without the technology. In terms of computing, for most people that would be precious little - it's just used as an easy-to-correct typewriter or an alternative entertainment centre. Compared with typewriters using lift-off tape, or playing games with friends, I think a reasonable case can be made that the progress is comparable with the shift from train to car (socially as well, perhaps?).

Returning to your and guests specific points: I well remember the first appearance of the 360 series computers. If we compare those things to wheeled transport, I suppose the equivalent would be a pre-pneumatic steam-bus - different combustion system to present versions (RTL, then TTL at series20 I think), etc.

The AppleII is probably a good starting equivalent for the PC. Best equivalent would be a model T - available, economic, owner-serviceable, and pretty-much did what it promised. For many tasks, the differences between the AppleII and even a CoreII PC are largely cosmetic. Even for complex simulation tasks, I would estimate the actual differences in performance are in the factor 100 region, rather than the 10^5 you would get from counting the number of components. If we measure logarithmically, I suppose that would be about halfway along the limit curve.

So far as I am concerned, it's all horses for courses. I know some ways the IC for computing* curve can progress that will be good for at least another couple of generations. Similarly, there are things that can be done within IC for cars** technology that are known in principle and will probably appear in the same timescale. I simply don't see that much difference between the uptake of what is known to be possible between the two technologies.

Fyz

*Integrated Circuits
**Internal Combustion

P.S. While I am picking nits, I imagine the actual power of your entire computing system to be closer to a couple of hundred watts if you include the peripherals?

Hi Fyz,

I must admit that you are correct and that trying to compare the automotive and computer/electronics industry is like comparing chalk and cheese and the parallels that I drew are pretty meaningless. They were done somewhat tongue in cheek to get a discussion underway.

However, I do believe that the car industry is very stagnant and incredibly slow to take advantage of new technology. I just watched a program about concept cars and there were some really strange looking vehicles but there was nothing new and the changes were all just cosmetic. One vehicle was so impractical that they had omitted to allow for seat belt mounts. The automotive industry, like too many industries, seems to engineer things backwards. They start out with what they want it to look like and then try and engineer everything to fit inside. Personally my engineering philosophy it to get the thing working properly and then worry about the appearance.

I recently saw an experiment that was done using some disused metal pressing dyes that were used in the manufacture of motor vehicles. With minimal modification the used the dyes to vacuum-form equivalent components from a polymer sheet rather than steel. The end result was a body panels that could be produced in the same amount of time, using existing equipment, that cost no more and possibly less from raw materials that only used a fraction of the energy to produce. Not only were there manufacturing gains but the resultant panels was corrosion resistant, a fraction of the weight and several times stronger than it contemporary metal counterparts.

So why are we still using steel to manufacture cars? The technology isn't that new, the materials are available and the manufacturing process is no more complex and in many cases simpler.

"The third point, and the one made by guest, is that you should be comparing what the technology has made possible compared with what is possible without the technology. In terms of computing, for most people that would be precious little - it's just used as an easy-to-correct typewriter or an alternative entertainment centre."

I must admit that most people have not idea of the potential for computers and to them they are a toy or just another annoyance. I was involved with Programmable Logic Controllers PLC when they were fairly new and to me the potential was only limited by the flexibility of the control engineer's imagination. While they are becoming more common they are not used in anywhere near all the applications that they are ideally suited. When they are used they are rarely used to their full potential and much of their complex computational ability is never used or implemented. I remember working on a PLC installation that was having a problem with input timing. This could easily be fixed with software but they instead attacked the system with a welding torch and moved all the sensors. The stupid thing was that they overcompensated and I ended up needing to do an identical software change except with different time constants..

The PC is the same and most people never use them to even a fraction of their potential. Personally I use a laptop for many things including, word processing, communications, photography, image processing and storage, calculator, fining system, medical records, music, planetarium, alarm clock, address book, telescope interface, navigation system, news paper, security system and the list goes on. The applications are limited to your own imagination and ability to use them as a tool. In my case I am continually finding new applications for it.

"While I am picking nits, I imagine the actual power of your entire computing system to be closer to a couple of hundred watts if you include the peripherals?"

Normally the only external device that draws power is a USB hub that draws about 5-10 watts. The reason for the USB hub is that I hate those touch-pads and crammed limited keyboards and there are not enough USB ports on my laptop. If I had everything that I connect, camera, telescope, GPS, backup disk, scanner, printer etcetera all turned on, then yes it would come out to around 200 watts but nearly all the time it's just the laptop and hub at around 75 to 80 watts. Of course that doesn't count the network equipment but we have a private LAN that connects 5 systems to a single broadband link so that needs to be shared

What would the power draw be if all the peripherals, if they were set up to use power as frugally as a laptop or cell phone?

Efficency=conservation

1 old fashioned tv driven by vacumn tubes, uses as much power as a modern refrigerator

If superconductor motor tech could be applied to a BEV what kind of range is possible?

the US spends $2billion/week on a bs war, a small fraction of that would go a long way towards reducing energy use by increasing efficency!!!!!!1

The problem with electric vehicles has been weight more than efficiency - and SFIK less than half of any losses occur in the motors and generators.

Yup

That is correct, the lack of efficency is the power source.

As Gwen has pointed out, the power density of liquid fuels is hard to beat.

The power density of batteries needs to be increased!

Or try this scheme out

A model helicopter turbine [ scrap oil fired ] spinning a generator

the generator & drive motor wound w/ nearly room temp superconducting wire.

Cast the battery housing as a stressed member of the frame [ or the entire frame ]

This would let the weight of the batteries work twice.

I'm probably missing the basis of your suggestion, as the only relevant bit I could find referred to reusing the housing of the battery as part of the frame. I don't know the latest score on motive-automotive batteries, but the last time I looked the housing was a small portion of the battery weight, the material was chosen largely for chemical rather than structural reasons, and it was important for the battery to be appropriately shaped for at least the following two reasons:
Minimising battery series resistance (already a significant source of electrical loss in many cases)
Matching the amounts of the various active constituents so that they limited the performance at the same point. Significant changes to the shape usually resulted in an increase in the amount of electrolyte - and consequent increase in total mass.

Fyz

Good stuff

the plates would be the heavy part!

so using them a stressed member would be problematic, since lead [ or other equally non structural battery compound ] & acid don't lend themselves, to hi tensile strength

Please elaborate more on the series resistance part, wouldn't most of the resistance be @ the connections?

Isn't the surface area of the plates, what determines the current?

doesn't each small compartment have the same potential [ voltage ]?

The turbine suggestion would actually belong on the hy-bred thread

The first point about the series resistance was that the plates of each cell need to be quite close together if the electrolyte resistance is to remain low. Orientation may also significant - I understand (not checked) that the simpler high-current cells become more fussy about charging cycles if the surfaces are too far from vertical.

The second issue is that the battery must still provide starter current for the motor if the vehicle is a hybrid. As the battery would be spread around the car if the housing were to make a significant contribution to the chassis, you'd either need substantial inter-battery wiring (more extra weight than you are saving?), or suffer high series resistance. Running at higher Voltages will ameliorate this, but I think the motors become more bulky (due to insulation requirements) if you go too far down this route (not my area of expertise, so I could easily be wrong).

Fyz

Fyz

The only point I disagree with is the increase in motor size with higher voltages. Especially in the realm of what voltages are practicably available from batteries the increase in voltage will normally result in a reduction in motor size, weight and system losses. High grade insulation is quite compact and light.

I'm sure that cars (12...24) volts are well below the voltages at which this would happen - but I'm imagining you'd need to run at over 100-Volts - and I've no idea whether this breaks that barrier. Can't see why the present lower voltages could increase the motor size though - you still need the same turns-current product; I could imagine you might need to enlarge the input wires and the commutator (or whatever is used instead), but that is all. The reason I feared increase in bulk due to insulation was not mainly increasing the thickness, but increasing the surface area due to longer thinner wires; also thinner wires might require more mechanical support and pack less well. That would increase the magnetic gaps, and so the amount of magnetic material needed, which would be where the weight came from. I'm sure this comes in somewhere - but you are probably right that we are a long way from that.

Fyz

Hi Emjay & Fyz,

"The only point I disagree with is the increase in motor size with higher voltages."

Design of electric motors was not my favorite subject at university and I really didn't pay enough attention but I seem to remember something about the best or most efficient voltage to run electric motors was something like 1.5 Kv. I have had a quick look on the net but cant find anything that can confirm or discredit this and it was 30 years ago so it could be completely wrong.

Certainly there are a whole host of variables in the design of electric motors and the voltage selection is not just limited by the insulation. If you are using a brushed motor then you need to worry about breakdown around the commutator. If you are using a brushless motor then you have to contend with the limits of the control circuitry and getting semiconductors to cope with high voltages and currents can be a nightmare.

Has anybody else heard this before or have some links that may confirm this or is it just my alcohol strained memory playing tricks on me.

I had heard something similar, but referring only to "traditional" motors/controls. Much depends on the design of the motor, and its use.

I came across this site which I found fascinating.

Once you move to ac from dc, efficency goes up

The next upgrade is 3 phase, as this decreases the wire size, then on to 5,7,9 phases. The # of wires increases but the size decreases dramatically. Like wise the # of power transistors increases, but the amount of current through each goes down.

Surely that must depend on the size of the motor? And isn't the "efficiency" of motors already very high - so weight would be more important; or did they mean weight all along? Sorry to be picky...

"Surely that must depend on the size of the motor? And isn't the "efficiency" of motors already very high - so weight would be more important; or did they mean weight all along?"

It depends on a whole host of things and if I remember correctly the biggest factor in the efficiency calculation was the hysterisis and saturation level of the magnetic media. The more residual magnetic flux that remains when the electric field is removed the more energy that is lost reversing the field and the less efficient the motor will be. The point at which the magnetic field becomes saturated is also important as well and once the magnetic flux has reached a saturation level in the metal any additional energy consumed by the exciting coil is wasted. To create powerful motors you need to have materials that do not easily saturate with magnetic flux and most of these materials have a high residual magnetic flux. The overall result is that the more powerful the motor the greater the losses and the less efficient the motor becomes. There have however been some huge advances in magnetic alloys since I was at university and so I am not up to date with what is and isn't currently possible.

You also have electrical resistance and mechanical friction plus the loss in either the commutating or switching mechanism that produce the rotation in the motor. Generally with resistive losses the higher the voltage the less pronounced they are but the magnetic flux that is generated by a coil is proportional to the current flowing in the coils so you have contradicting requirements.

All up it becomes fairly complex and unfortunately I am in the middle of moving house at the moment so my personal library is in storage. As a result I don't have access to the answers and so a real answer to the question will either have to come form someone else of wait till I can get my study set up again.

"Generally with resistive losses the higher the voltage the less pronounced they are". I assume you are referring to the back EMF. But whatever - this can only refer to results in a fixed design of motor. If you know the application Voltage, the number of turns in the coil will be proportional to the expected Voltage, and the current will reduce accordingly. The only intrinsic changes to the efficiency will be in the eternal series resistance (thicker wires required for the same loss at higher currents), and losses in slip rings or commutators (easier at higher Voltages), control gear. (N.B. It is in the nature of semiconductor design that HV devices are intrinsically less efficient than MV - but we are probably not working in a region where that is significant)

Within the motor itself, the only variable would be the amount of space wasted in winding inefficiencies (insulation and spacings). As it becomes difficult to make insulation too thin, there must come a point at which designing the motor for higher Voltages (thinner windings) means more space is wasted. At the other end, excessively thick wires must become difficult to shape - but maybe they become sufficiently self-supporting and so reduce the need for other structures.

I don't know the answers here - I'm just saying that taking lecturer's comments at face value (or is that merely out of context) can be misleading.

Hope the house move is not too traumatic

Regards

Fyz

HI Fyz,

"As it becomes difficult to make insulation too thin, there must come a point at which designing the motor for higher Voltages (thinner windings) means more space is wasted. At the other end, excessively thick wires must become difficult to shape - but maybe they become sufficiently self-supporting and so reduce the need for other structures."

One of the hassles with high current drain and large diameter conductors is eddy currents and that makes the higher voltage devices that contain longer but thinner conductors more efficient.

Losses in external devices like cables and connectors reduces with an increase in voltage according to an inverse square law . While voltage drop in mains voltage motors in negligible when we talk of low voltage motors (24 V and less) this becomes a critical factor and great care needs to be taken with conductors and connectors. Just look at what a slightly dirty contact can do to the efficiency and effectiveness of a starter motor and you will get the idea.

These are to areas where increasing the voltage is beneficial but there are negative and as you indicated the insulation breaking down is a problem. There is also the breakdown of the commutator if using a DC motor or the semiconductors if using brushless motors.

Another factor is the shape of the conductors and the packing density in a coil. I remember hearing of a problem with the conductor shape in a motor that was adapted from an existing design. I cant remember the details exactly but if I remember correctly the initial design called for square conductors and the copy used round conductors. I cant remember the exact problem the round conductors caused but the motors all failed prematurely and the motors needed to all be rewound using the original square conductors.

Electric motor design is an immensely complex subject and can easily and usually dose become a full time specialty. There have been some fantastic advances in magnetic materials and super conductors of recent and there are more variations in concept than most people have had hot dinners. As such there has been and more then likely will be further dramatic improvements in the efficiency, power density and ease of manufacturing in the not too distant future.

Hi Masu

Thanks - that all makes good sense - I'd forgotten about eddy currents in the windings - now I think about it, my recollection is that (at least with AC motors) you used to have to be careful about eddies in the magnetics as well. In any case, that would point to the optimum voltage not being too low - but still dependent on the size of the motor.

Regarding square windings - the differences would depend on whether the round windings were chosen for the same diameter (78%), to occupy the same space (could improve to 90% if the round windings were really carefully laid), or were laid in the same layering directions as the square windings (intermediate).
In addition, properly laid square windings will better conduct the heat out of the winding layers, and be more rigid.
Could be any or all of these things.

Fyz

I really should have paid more attention when I was at university and it is something that I will start reading about again once my study is ready and my books are out of storage. At university we had these lab kits that consisted of just about every type of rotor, stator, commutator etcetera, that you could think of. You could build just any type of motor/generator that you could think of by selecting the appropriate stator-rotor-commutator combination from those supplied and just dropping them into the frames that came with the kits. It was sort of Lego for electric motor/generator designers. There were some really complex configurations available and it was a lot of fun playing with them.

I just remembered an electric motor that you may find interesting. It was used to drive a cooling fan in a car that was built in 1983. The bearings started to make a noise due to wear and so I removed the motor and dismantled it to see if I could replace or repair the bearings. When I pulled it apart it turned out that it was entirely constricted from printed circuit boards. They just etched the shape of both the stator and rotor coils plus the commutator onto fairly heavy PCB material. A very simple elegant and reliable design that worked for over 15 years before needing any maintenance.

I ended up replacing the bearings with some teflon ones that I machined up and it was still working fine when I disposed of the vehicle a couple of months ago.

"Regarding square windings - the differences would depend on whether the round windings were chosen for the same diameter (78%), to occupy the same space (could improve to 90% if the round windings were really carefully laid), or were laid in the same layering directions as the square windings (intermediate).
In addition, properly laid square windings will better conduct the heat out of the winding layers, and be more rigid.
Could be any or all of these things."

I seem to remember something about the problem being to do with the rotors that were wound from the round wire deforming under high load conditions and coming into contact with the stator. Mind you it was nearly a quarter of century ago and I wasn't directly involved but coils can display some pretty weird properties especially when they are rotating at high speed. You can also get spot heating problems if the radius of the curve they are bent around is too tight and I have seen motors that have exhibited exactly this and burnt through the insulation.

Coming from a control background I am a fan of stepper motors and their poor cousins the brushless DC motors. In a control environment if you size the stepper motor correctly you don't need any feedback, all you need to do is keep track of the number of steps and which direction it has moved from the starting point and you know where they are. We used to use a lot of Printronix dot matrix line printers that used 4 phase 12 v stepper motors for the paper feed. One step corresponded to the movement of the paper by one row of dots. When we replaced them with more modern printers I made a point of removing the stepper motors and keeping them. They have come in very handy over the years.

I am currently building a digital camera for my astronomical telescope from an old digital camera I had. The problem is that the telescope needs to be focused differently for the camera than with a normal eyepiece. The plan is to drive the focusing mechanism with one of the salvaged stepper motors via a toothed belt to the focusing mechanism. Once I have found the best focus point for the camera it is a simple task of just keeping track of the steps the motor has moved through and stepping it back to the focus point for the camera. I havn't decided whether to use a separate microcontroller or a stepper motor controller via my laptop but either way the solution is considerably simpler than a DC motor and the added position encoder and the problems associated with speeding up and slowing down the motor.

I've found stepper motors are convenient for equipment control too. They may come in handy if you want to add tracking to your telescope...

I assume you are not placing the camera where you place your eye? If you could, the focal distance should correspond to the relaxed state of your eye - which is fine provided you are not long-sighted.

Fyz

The telescope actually has a computerized mount that once aligned can point to and track any of the several thousand objects that it comes programmed with. You can also add several thousand of your own objects.

It also has a RS-232 and Ethernet ports that you can drive it from. The software it comes with is pretty sophisticated and comes with a sky map that covers everything don to about a relative brightness of about 30.

If you drive it from the computer you can also use the software to keep track of the images from the camera and catalogue what you have looked at in the past.

"I assume you are not placing the camera where you place your eye?"

You assume correctly, it is what is called a Makustov-Cassegrain telescope and there are different ports for the camera and eyepieces. The second photograph on the link show the little brother of the telescope I have and the only difference is the size. These have several advantages over normal reflector but one of the big ones is that they are sealed and so the mirrors are not exposed to the atmosphere and prone to corrosion like in standard reflectors. Another is the arrangements give you a much greater focal length that a similarly sized reflector. The one I have has a 1,900 mm focal length yet is less than 500 mm long overall. A similar reflecting telescope would be over 2,000 mm long and considerably more difficult to operate and set up.

To give you some idea of the sort of resolution here is a photograph I tool back on 12^th April and show a crater that is called the Bay of Rainbows. The Apollo 15 landing site is roughly where the © symbol is in the bottom right hand corner. This was a test to see what could be achieved with the camera stuck over the camera port and held in place with blue tack and a guess at the focusing. Once I build a proper mount and focusing mechanism the results should be even better.

Nice picture.

Note: Because they use all-spherical components, Maksutov-Cassegrain telescopes tend to be large for their performance (though not as large as pure reflectors - and you don't need to stand on a platform to use them either...). Given the ease with which modern equipment produces aspherics (US$50 retail for a pair of custom spectacle lenses, for example), I'm surprised the world hasn't moved on*. However, the Maksutov design does produce excellent performance within the design field-of-view.

*It's quite a few years ago now that an optical designer friend had a contract to create an arrangement with the sealed characteristics of the Maksutov but using aspherics to make it suitable for larger apertures

Maybe we should let this thread get back to battery vehicles?

Fyz

Talking about Coil Technology, here is an interesting design used by ThinGap:

( http://www.thingap.com/press/pr052306.cfm )

The "ThinGap motor is made from precision-milled sheet copper in a fiberglass and polyimide material composite, rather than from conventional copper wires."

There is also an advantage in Brushless Motors in that the windings are placed in the stator, instead on in the rotor in a brush-type motor. This removes the rotational stresses from the windings, although there will always be significant magnetically induced forces.

I have used Stepper Motors for years because of their simplicity in producing complex motions accurately. However they are inefficient and highly prone to resonances due to their "start-stop" stepping action. Brushless DC Motors are a way to still enjoy the discrete positioning motions of a stepper, while minimizing resonances and maximizing power density. They can be driven in step fashion using square or trapezoidal commutation, or driven with a simulated sine wave. I $10 microcontroller could even switch between sine & step while running. (of course, these techniques can also be applied to conventional "steppers", but less smoothly.

For really heavy currents where multiple parallel conductors are used, square or rectangular conductors are commonly used and the point where the conductors are crossed is critical to the end result so that the DC resistance and the impedance are matched as closely as possible. Unless the overall impedance of parallel conductors is matched they will not load share, resulting in major loss of efficiency.

From a propulsion perspective the brush type DC motor is on the way out, for instance over 50% of locomotives are being built in AC configuration despite a hefty price premium over DC. In Off Highway Vehicles this trend is also catching up. Current design technologies are; GE / Komatsu / Terex etc., 3 phase squirrell cage motors with either GTOs or IGBTs in the inverter stage, Siemens / Komatsu / Hitachi as above, Mitsubishi / Caterpillar 3 phase squirrell cage and IGBT inverters, Le Tourneau use Switched reluctance motors and Belaz are using a strange AC technology that I don't have the full details of yet.

Passenger and other on highway applications can and do use these technologies for instance Tesla Motors use IGBT / Squirrell cage.

Use of AC motors eliminates any drawbacks from higher voltages and increases overall efficiency as well as responsiveness. Other advantages are fine torque control as well as slip / slide control.

One of the areas that has produced huge improvements in the performance of electric motors of recent is the application or rare earth metals in the magnetic medium.

There are a couple of problems that crop up with electric motors is hysterisis or the amount or residual magnetic flux that is present when the current through the exciting coil is removed. The higher the residual magnetic flux the more current must be pushed through the exciting coil before this is cancelled and the magnetic field reversed.

Next you have the point at which the magnetic medium saturates. Once the magnetic medium is saturated no matter what you push through the exciting coil there will be no increase in the strength of the magnetic field and therefore no increase in the output of the motor.

Finally you have the heat problem, both of the previous problems will result in the generation of heat within the motor and most magnetic materials will not perform as well with elevated temperatures and the build up of heat both reduces the efficiency of the motor and causes even more heat to be generated.

There have been some fantastic improvements in the field of magnetic materials over the last decade or so and this has allowed the production of smaller, more powerful and efficient electric motors.

Masu,

Rare earth magnets are certainly making their presence felt, especially due to falling cost. Permanent magnet brushless DC motors are central to International Rectifier's plan to reduce energy wastage in China. We can soon expect to see them in Chinese appliances for the world market, notably Airconditioners which are expected to come in at price points similar to standard induction motors but with efficiency similar to Japanese inverter models.

Some current inverter designs regenerate from the decaying field as well as controlling saturation. Inverters have been delivering efficiency gains for years which far out weigh the switching losses in the Semis. Underneath that is the inherently high efficiency of the three phase motor, which has never the less been further optimised by modern manufacture (the paybacks are there due to long run times). Hysteresis losses and eddy currents have long been controlled in both power transformers and motors. Choice of alloys controls hysteresis and laminations control eddy currents, mass production and high operating hours continue to fund research and development in improved efficiency.

Heat is not an insurmountable problem when devices are used within their ratings, modern high efficiency motors are allowed to run hotter to save on cooling losses. Transformers on the other hand are routinely rerated to higher power levels as the cooling is stepped up. Initially a transformer may be installed as ONAN then as load increases it is converted to ANAF or OFAN, then the last stage currently is OFAF. As clean coal technology comes into being, power transformers and large motors have another series of stages available in the form of dead loss or even heatpumped CO2 cooling. The real limiter will be, as you say, iron saturation not heat.

Well put.

Size and weight have a rough inverse relationship to Voltage. The voltage levels of large motors keep going up, 11kv and 22kv 3 phase motors are increasingly common in high power ratings. You would be surprised at how compact (and light) a 5000hp 22kv motor is especially when compared with an ICE.

It is impossible to use the battery housing as a member of the frame.

As stated by others the battery housing material is chosen on chemical resistance and is stresses would be applied the chemical resistance would be reduced (taken into account that the material could take the stresses after all)

A second casing is always needed in case a battery would leak. After all, we are building a greener car isn't it?

interesting evolution at a motor supplier check it out.

http://www.pmlflightlink.com/archive/news_mini.html

They have a series of articles on this.

I noted that the super-capacitors were just lightly touched on and mentioned that they were dangerous in an accident. I dare say they are no more dangerous than the highly flammable and possibly explosive fuel now used in IC vehicles. Their design and development is still in its infancy with respect to heavy industrial uses, such as transportation.

A different technology that I have as yet seen not mentioned is kinetic batteries. If I remember correctly there was at least one vehicle that used such a system in the infancy of the automotive industry. Manufactured in France if memory serves correctly.

Commercial high speed / small size units are already in use in the space sector for energy storage on board satellites. These same units have been used successfully in prototype hybrid race vehicles from a number of automotive manufacturers, Mercedes was one and a US car maker used a similar concept later on as well.

The downside of high speed kinetic batteries is that they are high speed. This requires specialized bearings, evacuated cases for higher efficiency and specialized materials for the components to provide safety in case of failure.

Now low speed kinetic systems don't have the issues of catastrophic failure but do have the problem of frictional losses to contend with. As an example of something similar already in use is a fan used in a building cooling system. Most fans used in such systems are a meter or less in diameter and require a 1/4 hp electric motor. A large office tower system would need several dozen or more such fans for moving air over the cooling systems. The unique solution was to use one horizontally mounted fan the size of the building roof and driven by 2 motors of 1/4 hp each. The unit took 2 hours to get up to speed but only needed 1 motor to compensate for frictional losses to keep the fan rotating at operational speed.

For automotive use of course the smaller high speed kinetic batteries would be of most practical use. In their favour is higher energy densities and high current transfer rates. Problems for now is capacity and cost of the off the shelf units.

Apologies for the bit of rambling. Now back to the regularly scheduled "discussion".

The problem with capacitors that makes them worse than a liquid fuel is the time that it takes to dissipate all the energy. With a burning fuel is can take several minutes.

A capacitor on the other hand can expend all its energy almost instantly which can end up creating catastrophically high temperatures.

Mind you they are both something that I would definitely try and avoid so by that measure they are equal.

When you speak of kinetic batteries I assume you are talking to flywheel energy storage systems where the energy is stored as kinetic energy of a rotating flywheel.

There are a couple of problems with these systems.

1. The amount of energy that is stored in the system is proportional the mass and square of the rotational velocity. That means the faster you turn then the more efficient they become . As a result you really have no option but to make them go as fast as possible and that means some tricky problems with the bearings.
2. The other hassle is the gyroscopic effect. If you thy and change the orientation of the axis of rotation you are in for a bug surprise. That because any force applied to it will result in the force being translated through 90°. So, if you have a vertically aligned axis and start to go up a hill you will end up turning the vehicle to the right. Back in WWI some of the earth used what was referred to as radial engines that had all the cylinders rotating around a fixed shaft. It worked well as it allowed for better cooling and a better power to weight ratio. Unfortunately the gyroscopic effect made the aircraft extremely difficult to fly and killed more pilots that were shot down by enemy aircraft. The concept was soon dropped and engines with to either a fixed radial, in line or V format. There are some ways to get around this by having multiple fly wheels or mounting the flywheel in a gimbal frame but this makes them heavier,. More complex and difficult to construct.

The concept of storing energy in a flywheel has been around for a while and it is used in fixed installations but from what I have seen the mobile versions were too problematic and never really caught on.

Counter-rotating flywheels wouldn't be so bad as regards effects on the overall vehicle - but I fear the the gyroscopic torques would prove problematic for the bearings.

Fyz

Counter rotating or not all that rotating mass would still resist changes in direction.

• Counter-rotating flywheels wouldn't be so bad as regards effects on the overall vehicle - but I fear the the gyroscopic torques would prove problematic for the bearings.

I havn't given the concept of counter rotating flywheels a great deal of thought but it the concept of having a large mass spinning at high speed tends to make me tread carefully. The gyroscopic effect has a nasty habit of sneaking up from behind and biting you when you least expect it, often with catastrophic results.

When I was a cadet engineer I spent six months working in Honeywell's instrument repair facility. I never saw it done but the boss told me how they had a fairly harmless looking box they used for putting annoying individuals in their place. It was reasonably heavy weighing around 15 kg and they would bet that the annoying individual couldn't carry it to the end of the corridor, round the corner, down to the end of the next corridor and back again within 30 seconds. Initial impressions would tend to indicate that while you would need to work hard it was within the ability of most reasonably healthy individuals.

However, like most dares and bets with engineers there is often more than meets the eye and the trap here was most of the 15 kg mass of the object was made up with a thumping great gyroscope. What they would do was line the axis up with the corridor then spin it up using compressed air. Once up to speed two assistants would carry it out to the unsuspecting individual in the corridor without changing its orientation. The victim would then be given the command to go at which time they were to take the box from the assistants and head off on their short journey. Things would go fairly well till the unsuspecting victim got to the corner and tried to do a right hand turn at which time the box would do a massive nose dive taking the unsuspecting individual with it. You can just imagine the look of confusion on the idiots face as they tried to work out what on earth was happening.

The same boss also told me how they used to spin up bearings using compressed air and then send them off across the workshop floor at frightening speeds. Unfortunately one day when they were trying for a record speed it got out of control and the bearing shot off across the workshop, through the wall and out onto the tarmac outside where there were several aircraft parked. They never found the bearing but had to do a very thorough inspection of all the aircraft in case the bearing had hit them and caused serious damage.

I can't understand why but the occupational health and safety people take a dim view of fun like this and have pretty much stamped it out. What spoil sports!

Assuming the flywheels were similar in all respects except direction of rotation, the torque required to turn the flywheels in any direction (other than there direction of spin, which is not an issue) would be equal and opposite. That would generate (large) torsional stresses on the bearings and the casing, but no net external force. Twin propeller aircraft and counter-rotating double propellers benefit from this cancellation (although it is often only partial with the double propellers).

But, like Masu, I would feel the need for a very high level of well-defined testing before trusting to a mechanical system with such a large amount of stored energy. I have seen the results when a 12"/3kg high-speed rotating disc disintegrated due to a manufacturing flaw: the surround was destroyed, and there were deep holes in the wall of the room. Fortunately, the system was designed and used safely, with a vertical axis, horizontal shields, and placed well above head height, so no-one was hurt.

Fyz

• Twin propeller aircraft and counter-rotating double propellers benefit from this cancellation (although it is often only partial with the double propellers).

With the ditching of the rotary engines that had the cylinders whirling around at considerable speed, the gyroscopic effect has been fairly insignificant. The major problem is prop wash which is a sort of vortex that is caused by the propeller and cases a yawing and rolling effect when it hits the tail fin.

They tried to get past this with the de Havilland Mosquito by having a single tail fin outside the prop wash and engines and propellers that rotated in opposite directions, but this introduced some very undesirable consequences. Because the tail fin was outside the prop wash the effectiveness of the rudder was proportional to the air speed and as a result the effectiveness of the rudder was considerably reduced at and shortly after take off. A problem with or failure of an engine while the air speed was low at and shortly after take off would produce a yaw that was greater than could be corrected by the rudder and result in a unrecoverable spin.

If you look at many of the twin engine aircraft that were produced around the time of the Mosquito like the Messerschmitt Bf-110 and P-38 Lightning you will see they had twin tail fins place behind the props. This meant that the air coming from the pops was flowing over the tail fins and while this did give them a problem with prop wash induced yaw and roll it did mean the rudders were effective enough, even at low air speeds, to overcome the effects of a engine failure induced yaw.

Getting even further off track for a moment, the problems of rudder ineffectiveness on multi engine aircraft is still with us. With multi engine jet aircraft the yaw produced by an engine failure means you will run out of rudder at speeds considerably greater than the stall speed of the aircraft and many modern aircraft have the same problem that plagued the Mosquito. In 1991 an RAAF Boeing 707-368C was lost killing the entire crew of 5 in very similar circumstances. They were on a training flight to practice asymmetric operation, or operation with one engine shut down, when they let the speed drop too low whereupon they ran out of rudder control and ended up in an unrecoverable spin.

Getting back to the gyroscope effect with aircraft the counter-rotating props are normally there to counteract the yaw and roll induced by the prop wash rather than to counteract the gyroscopic effect of the spinning crank and propeller. This would certainly seem to be confirmed by multi engine jet aircraft that are now so common. The have humungous compressors and turbines rotating at seriously frightening speeds but they all rotate in the same direction so the gyroscopic effect can't be something that is not controllable with conventional control surfaces.

Yes, I can believe that twin counter-rotating engines have not found application in modern aircraft -and in general, the larger the aircraft the smaller the proportion that is taken up with drive, so it is no surprise that economy of part-stocking has become more important than balancing gyroscopic or wash effects. However, having said that, as an outsider I keep hearing about the merits of using twin counter-rotating propellers within a single air-stream; these are said to include improved aerodynamic efficiency, reduced wash effect and requirements for external structural stiffness to counter local gyroscopic torque - although I am no position to judge whether that is all theoretical BS or not. (I'm not certain what will be the position for small highly-manoeuvrable fighters as range starts to become a significant parameter)

However, that was just an example that may well have become outdated by changes in engine design. The point was to show the theoretical compensation had found practical application (which is the best-known verification of a theory, I think), rather than to imply that it might be universally required or used.

Hi Fyz,

• However, having said that, as an outsider I keep hearing about the merits of using twin counter-rotating propellers within a single air-stream; these are said to include improved aerodynamic efficiency, reduced wash effect and requirements for external structural stiffness to counter local gyroscopic torque

Back in my powered flying days in light aircraft you certainly needed to put in a hell of a lot of right boot when the aircraft was traveling slowly and you had the power set to take off or climb. When doing circuits and bumps, which is what trainee pilots spend most of their time doing, you soon end up with a very sore right knee and thigh from trying to keep the darn thing straight. It seemed to be worse with Piper than Cessna aircraft but I think that had a lot to do with the position of the wing and tail fin which were lower on the Piper than the Cessna aircraft.

However and interesting point to note was that was when you reduced from take off and climbing power to cruising power the amount of right boot you needed to apply reduced dramatically and you never bothered to use rudder trim to counteract the effect till you had the aircraft set up in stable horizontal flight.

The requirement for less correction when cruising was partly to do with the speed which was considerably higher when cruising that take off or climbing making the rudder more effective, but from what I was taught the major component was the reduced torque coming from the engine that was trying to flip the aircraft over.

My pilot training was some 30 years ago now but I have been thinking and I never recall anybody mentioning the gyroscopic effect. They did, however, talk about the engine torque and prop wash affecting the control and what you needed to do to counteract it and keep the aircraft under control. It's quiet possible that compensating for any gyroscopic effect was limped in with the torque and wash problems but they never mentioned it at the time. It might take a while but next time I get a chance to corner a flying instructor I will ask about it.

There is something else and that is the relatively low speed that modern piston engine aircraft operate. The normal range of engine speed is from idle at around 1,000 RPM to maximum power at around 2,800 RPM with normal cruising being around 2,500 RPM. Training aircraft are usually pretty simple and just have a throttle to control the power but the more sophisticated aircraft don't have a throttle as such. They have three separate controls mixture, pitch and boost which you need to use in combination with each other. The idea is to always operate the engine at its most efficient RPM usually around 2,400 to 2,600 RPM and then use the pitch and boost controls to gain the required thrust for the particular mode of operation. For example, on take off where you require maximum thrust at low speeds you have the pitch fully fine and the boost as high as possible. When cruising where you want to have the greatest speed you have the pitch set to almost fully coarse and the boost pressure much lower. The mixture control is used to reduce the fuel consumption but it is also used to cool the engine. If you increase the amount of fuel past the point of maximum efficiency the un-burnt fuel is evaporated and takes much of the excess heat out the exhaust with it. You normally operate aircraft engines on the rich side as there is less chance of damaging them.

Just as an aside, when I converted fro powered aircraft to gliders I was astonished with the amount of rudder you needed to use. It's related a couple of thing called secondary control effects that many are unaware of. When you apply aileron input you change the profile of the wings slightly so that one wing produces slightly more lift than the other. As a result the wing that is creating the greater lift will have slightly more drag than the reduced lift wing and this will cause the aircraft to yaw in the opposite direction of the bank. This is called the secondary effect of ailerons and to overcome it and keep the aircraft balanced you use the rudder to compensate for the yaw.

The other effect is the secondary effect of rudder. When you put on rudder control it causes the aircraft to fly in a large circle and as a result the wing on the inside will be travel along a slightly shorter path than the wing on the outside. This slight differential in distance causes the outer wing to travel faster and create more lift than the slower inner wing and the aircraft will bank in the direction of the rudder.

The whole idea is to balance the use of both rudder and aileron so they negate the secondary effects of each other. On gliders the secondary effects are so much greater as the wings are so much longer and therefore have a greater effect on the aircraft requiring more rudder input to counteract. On gliders we use a highly sophisticated instrument called the yaw indicator to indicate how balanced the aircraft is. It consists of a piece of wool around 100 mm long in some ludicrously bright colour that is attached to the middle of the canopy using a piece of electrical insulating tape. If you have the rudder and aileron controls set correctly the piece of wool will be in line with the axis of the aircraft. If you look carefully in movies like Top Gun that have sequences showing get powered fighter aircraft you will often see they use the same instrument.

You also need to be careful when using rudder and aileron while the aircraft is flying near its stall speed. You can very easily end up slowing one of the wings down below the stall speed and put the aircraft into a spin where you have one wing flying and one wing stalled. During the early days of aviation many pilots were killed when they got their aircraft into a spin. It wasn't till near the end of WWI that they developed the spin recovery technique that all pilots are now taught. Basically you push the nose down neutralize the ailerons and kick on full opposite rudder. When the spin stops you centralize the rudder and pull the aircraft out of the now close to or sometimes over vertical dive. Believe me, spin recovery always gets the old heart thumping even after having done it numerous times.

Anyway, I do apologize, I have been waffling about aircraft again, its just aircraft, aviation and flying are such incredibly interesting and fun topics it's hard not to.