Gen-set/APU, Can it be used to make a homemade Hybrid?

Gas = petrol???

If you have a petrol generator in the car of course you can use the output to drive a electric motor.

But why?

It would be much more efficient to use the generator motor to drive the wheels...

In Diesel trains, the diesel runs a generator, and the electricty drives the wheels, when you go into braking with Electricty, you dump the generated power back into storage batteries, or a resistor bank.

If your driving the wheels with the diesel engine, you use gate braking to slow down the vehicle, the same as what trucks use, and all the little signs in residential areas "Please don't use Gate Brakes in this area"

gate braking?????

Is this a term used for using the gears and engine to slow down?

Here, in the US, it's called a Jake brake. It is a compression release, so that on trailing throttle (in a diesel) the energy used in compressing air in the cylinder is lost to atmosphere, instead of being retained and helping to move the piston back down like a spring. They make quite a racket, so their use is restricted. In mountainous areas, however, they are almost essential to avoid brake fade and excessive brake wear.

No, it refers to closing a gate in the exhaust to slow the truck down. Originally (I think) an accessory made by Jacobs Company, thus, at least in the USA, the slang term "Jake Brake". -- JHF

Not to split a point too fine, but the actual name of the braking system being discussed is "jake" brake, after Jacobs, the company that pioneered and now dominates engine compression braking systems for Diesel engines. It consists of modifications to the engine valve train that when activated, allows the engine to be driven by the drive wheels and thus converted to a compressor which can absorb up to 600 HP. It also makes an ungodly noise, which is why the signs at the entrances to some towns. This braking system is primarily intended to slow heavy trucks on grades to save the service brakes.

Wow thanks, never heard it called that in the UK...

So its a form of decompression valve for the cylinders to allow the engine to brake the wheels...

I bet that does make a hissing good sound!!!

No. It makes a very loud banging sound.

j.

I'd describe it as more of an 'owl! as if the exhaust valves were being pulled out through the silencer

In the UK we call it an exhaust brake or ..... I can't remember but my trucker buddies have a slang name for it here. It literaly closes of the exhaust, and so slows the amount of gas that can leave the cylinders, via the valves. In essence creating a compression on the cylinders, which slows everything down. It is usually a small button on the floor of the cab near the brake, that you depress with your heel before you use the actual brakes. Stops the brakes overheating when going down long hills.

Close, but actually, it opens an exhaust valve right after the air is compressed in the cylinder. Otherwise, this compressed air pushes the piston back down, recovering the compression energy and delivering it to the wheels. By releasing the air after is it compressed, you've expended the energy to compress the air, but then let that energy out into the atmosphere -- thus the loud machine gun noise.

see http://en.wikipedia.org/wiki/Jake_brake

BTW a reverse of this is used in modern 2-4-6 (variable displacement) cylinder engines. When a cylinder is shut off, its valves stay closed, so the cylinder-piston combo acts as a spring, avoiding the pumping losses of a lightly loaded cylinder. Counterintuitive, perhaps.

in USA valve timing is jiggled to increase pumping losses; in Europe exhaust passage is obstructed (same reason)

I bet that does make a hissing good sound!!!

I am reminded of a slow rate of fire machine gun, only the sound is much deeper and much louder. Da Da Da Da Da... at a rate of about 4 Das per second.

Bill

I think you mean "Jake Brake" as opposed to "Gate Brake."

Jake braking is when air is introduced into the truck cylinders when the accelerator pedal is let off. The air is compressed by the engines pistons and exhausted which dissipates some of the kinetic energy of the moving truck thus slowing it down. However, exhausting the compressed air creates a very loud rapping noise, thus the objection to use of the Jake Brake in residential neiborhoods.

I feel you are right,only concern is that gas might be expensive to run enough power.

WHAT????

As a follow-up:

If you were to make the APU modular & removeable, reduction in mass would greatly increase range 'around town' when you can operate 'all electric'; re-installing for holidays & the like.

Toyota calls it a Prius - ( with a battery pack )

Yes it works fine - BUT - Start with an efficient gen-set - run it with chemical additives and Hydroxy - feed the battery bank - - use an old apu generator for the motive power

add a regenerator circuit if you are able to build it

expect lots of questions from folks in the street

The folks who have done it like it - and laugh at the folks who keep saying "there is something wrong" -

rcb

Yes it has been done.

http://www.motherearthnews.com/Green-Transportation/1979-07-01/An-Amazing-75-MPG-Hybrid-Electic-Car.aspx

Link is an article in 1979 about an Opel GT getting 75 MPG after being converted.

The basic rule is that energy/matter cannot be created nor destroyed.

Therefore, you certainly can run an electric motor driven car off an onboard petrol engine driven electric generator. Nonetheless, to do so is to introduce, between your petrol engine and your propulsion motor, inefficiencies that would not be there if you simply propelled the car with the petrol engine.

It just occurs to me that the hybrids hide part of the cost of operating by using house current to charge batteries so that if you calculate the mileage the onboard gas engine gets per gallon of petrol, the mileage is better because part of the energy used to run the car was house current stored in batteries.

Now those, the car manufacturers, are one slick bunch of operators, real con artists.

All that notwithstanding, there are conditions under which it would be appropriate to run an electric car from an onboard fuel burning engine powered generator.

One of them is access to a cheap form of fuel that a recip engine won't digest, for instance, powdered coal, or dried powdered organic matter, etc.

Those types of fuels, without considering how dirty they might be, could be blown into a turbine engine and ignited, turbine engine driving an onboard generator.

So yes it can be done but is only efficient in terms of cost under very special circumstances.

j.

I disagree. Electric is 4-5 times more efficient than gas so I am not sure the special circumstances to which you mean. The basic law of physics you quote when you say energy/matter cannot be created nor destroyed assumes it takes an equal amount of gas to power a generator as it does to power a car doesn't account for how inefficient gas is in combustion engines (less than 1% is used to accelerate the driver).

Nor or you taking into account that you can capture wasted energy by braking electrically, which cannot be captured in your typical combustion engine. (keyword typical)

Let's see... to, as you put it, to accelerate the driver you need as well to accelerate the entire bundle, the car and the gas engine moving the car. In the case of the electrically accelerated car you need to also accelerate the driver, the gas engine driving the generator, and finally the electric motor and the car it is accelerating.

Then you apparently do some voodoo mathematics taking into account the gas needed to "accelerate the driver" leaving out the various other things needed to be "accelerated" and announcing that you need just 1% of what to "accelerate" just "the driver."

When I recently went to university I kept telling the remedial math instructor the voodoo new, new, math was useless.

If you went to school recently you may be my case in point. But, in case I simply do not understand you please supply actual numbers.

And prithee do tell us, accepting for the moment your 1% number, in "accelerating the driver" are you speaking of accelerating him on roller skates and if not what happened to the car, the generator, and the engine running the generator, including all the apparatus necessary for salvaging energy from the braking process.

j.

What a rant, I feel sorry for anyone who took the time to read that. The point was how ineffecient combustion engines were, the numbers. ok. . . .4-5 times less efficient than gas (400-500 percent), now where is that doll that I jam my needles into :) voodoo boy.

It is time to reread what Blink has to say regarding the route to efficiency. This is a similar route to that used by locomotives and Off Highway Vehicles.

The fuel cost with an Electric drive OHV is around 50% per tonne of dirt moved when compared with Mechanical drive machines (despite regenerated power during retard not being recovered). The Electric drive units are faster on ramp despite utilising smaller engines than the equivalent tonnage rated mechanical drive. Mechanical drive systems that utilise torque converters and differentials are inefficient. This is why two seperate wheel motors are used instead of a single drive and diff.

Hybrid OHVs and Locos are under development though

The cheapest hybrids use big (30-40hp) DC motors. If it takes ~30hp to push a fairly aerodynamic sedan at 55mph you'd need at least this big of a generator onboard.

Off-the-shelf generators are very square and might be a bit tough to fit into a car. Does anyone know of any places you can just buy a DC generator with these kinds of power ouputs? I've always wondered if it would be worth it.

Refer to Rieds link posted earlier which is: http://www.motherearthnews.com/Green-Transportation/1979-07-01/An-Amazing-75-MPG-Hybrid-Electic-Car.aspx

You can get gensets of this size, but often a cheap way to get a large generator is to buy a surplus motor. The machines are essentially identical (in fact, any motor is acting as a generator -- generating back EMF -- whenever it is running).

I'd say it is definitely worth it, if you have the time to experiment.

I can't get my head round this...

If you're going to have a petrol engine driving a generator to drive elec motors for propulsion... and you are saying this is more efficient due to the engine operating at its peak efficiency rpm, load etc...

What ever happened to the infinitely variable 'gear boxes' that were tried out in the early 70s that meant the petrol engine always ran at a constant speed and load i.e. at its most efficient?? I think it was Datsun who tried this method with a belt drive, but by now better methods must have been designed.

Wouldn't a simple infinitely variable gearing mean that it would be much more efficient to use a petrol engine alone rather than incur the losses of conversion to electricity and power by generator and motors ???

Okay I can see that you won't get regenerative braking this way, although dc motors could still be fitted to reclaim this 'lost' energy...

John.

I understand, but I think the variable gear boxes confuses the matter rather than clarifies things. No one will say gas is more efficient than electrical because combustion is not an efficient process, that is why electric is 4-5 times more efficient.

But pound per pound, gas holds 120 times more power than a battery, "who killed the electric car" has no merit when you consider that fact, so the question becomes can a lawnmower size engine suffciently power a 400-amp DC motor generator like the one mentioned in this article:

http://www.motherearthnews.com/Green-Transportation/1979-07-01/An-Amazing-75-MPG-Hybrid-Electic-Car.aspx

And I quote from the article: "Then, to provide a consistent source of power for this motor (and to supply an energy storage bank), the engineer installed four 12-volt, heavy-duty automobile batteries-in series-which are "fed" by a 100-amp generator that's run off a 5-horsepower lawn-mower engine."

In theory it sounds good, will it work I don't know and I read the article. It seems like one would rather pay for gas for a lawnmower than a gas engine, but boy that sounds way too good to be true.

No one will say gas is more efficient than electrical because combustion is not an efficient process, that is why electric is 4-5 times more efficient.

But surely that is exactly what is being said - This thread is about using a petrol engine to drive a generator which in turn drives the motors for propulsion, the motors if not used the generator tops up the batteries, and braking is regenerative to top up the batteries...

But the whole start of the propulsion train is the petrol engine is it not???

Electric motors maybe more efficient than petrol motors but if they have to run from a petrol driven generator.......

John.

That's a fair point but look at some locomotives, they are using diesel to produce electricity to run the trains, and its tough to argue that the engineers are doing that backwards. So ask yourself why would trains do this? Then the question becomes, is it possible that the inefficiency of the gas powered mower charging system is more efficient than that of the gas car engine?

Locomotives run 2000-6000+ horsepower. Try to design a small transmission to drive wheels at that power.

Diesel-electric locomotives replaced steam power due to ease of repair, low maintenance costs, and good reliability. Efficiency is not all that greater than steam power, but overall cost of operation is a lot lower.

Sbruel,

Ried offered you some numbers. Good ones. But max horsepower is not all you need to make a true comparision.

What is the load those engines are pulling. Horsepower to horsepower how does that compare to car?

Beyond that Ried correctly points out the need to replace gear boxes, something necessary with diesels, with continuously variable electric drive.

Steam, which came before diesel, did not require transmissions because its power output is related to steam input which can be continuously varied.

Superficially apples and oranges look the same but they are not.

Perhaps you are looking at the same problem when you try to compare diesel electric locomotives and diesel or gas electric cars.

j.

Exactly!!!

j.

Parts of it are too good to be true, thats why we're not all driving hybrids yet!

Range on the MEN Opel GT was pretty limited, due to the small HP and small battery pack.

The lawnmower engine/generator did not directly power the DC motor on the Opel. The motor is powered from the storage batteries. The batteries receive energy from both the small generator AND from regenerative braking through a DC motor power controller. In the article, you may have noted a statement about performance issues with mountainous areas and long hills.

This effort was by a backyard tinkerer resulting in an imperfect vehicle, but does have some interesting performance claims. I offered it as fuel for discussion, not something to solve the world's energy problem.

Actually the battery power is used for over 50 mph

"Then, to provide a consistent source of power for this motor (and to supply an energy storage bank), the engineer installed four 12-volt, heavy-duty automobile batteries-in series-which are "fed" by a 100-amp generator that's run off a 5-horsepower lawn-mower engine."

The theory is roughly correct, but the engineering is not quite right. To charge at a high rate, the generator output would need to be 4*14V or about 56 volts. 56 volts at 100 amps is 5600 watts. 5600 watts is 7.5 hp. Given 80% generator efficiency (about the max you'd expect from a starter motor) you'd need over 9 hp from the engine. Even this would be on the low side of reasonable for a 2100lb car.

But the idea is basically sound, and would be easier to do today with electronic controllers than it would have been in 1979, when I think their price would have been quite high.

so the question becomes can a lawnmower size engine suffciently power a 400-amp DC motor generator like the one mentioned in this article:

If you mean directly, the answer is no. 400 amps at 48 volts is 19,200 watts, or about 26 hp. But a moderately large set of batteries can output that current for a couple minutes at a time. So the principal is fairly sound. If you only drove around town all day, and had very rare bursts to 50 - 60, then even the 5hp motor could keep the batteries topped up - its just cutting things a little too close, in my opinion.

I've done some test drives around the suburbs here, and trip average speeds are very low -- often 25 mph, even when traffic is light. But suppose the 5 hp engine runs constantly using 2.5 lbs per hour (.38 gallon per hour.) If that gets you 25 miles, you're getting 65 mpg. Pretty good. So even with 5 hp, his 75 mpg figure could be correct, given the right terrain and traffic conditions.

It would be a fun project.

Bravo...very well put. Nice post. I'll be sure to link back to it...these kinds of discussions do come up often enough to warrant it.

Thanks, I appreciate your feedback.

What ever happened to the infinitely variable 'gear boxes' that were tried out in the early 70s that meant the petrol engine always ran at a constant speed and load i.e.

An infinitely variable gearbox will allow a petrol engine to run at constant speed but not at constant load.

If someone were to drive a vehicle that is capable of 70 MPH at 15 MPH they could keep the engine speed constant but there would be no way of keeping a full load on the engine.

You can use the excess capacity to charge batteries and if the efficiency gained by keeping the engine running under full load exceeds the efficiency lost by the generators and motors then it makes sense to do so.

I'm looking for a generator setup as a 'plugin' module to a purely electric car so the odd extended trip is possible. I live in the montreal region and a 100km range (100% electric...from lithium batteries) will allow me to do 95% of everything I want/need to. LONG trips are always family affairs and we take the minivan. A module for the car that would allow me to make longer trips would be 'nice' but not at all necessary for me. Just an interesting way to pass the time. I was thinking of using one of these cargo platforms that attached to the hitch hole on the back of a vehicle. This would put the extra bulk right in the void behind the car and not be contributing significantly to the drag as would be the case if it was on a small trailer. Then again, I wonder if there isn't a way to configure a small diesel engine to drive the wheels at cruising highway speed (once the electric gets the vehicle up to speed and deals with all the little stop/go traffic) and that way the electric motor could be used to provide some charge to the batteries during the long legs of a trip...a parallel hybrid setup instead of series.

Anway, I'm starting to think out load so I'm signing off for the weekend. Have a good weekend everyone!

I seem to recall Honda having a concept electric vehicle with a small aerodynamic trailer housing a generator for long trips. Was it on a Civic platform?

We played a bit with the gen+trailer when i worked @ Solectria.

Had a great permanent magnet 3ø unit coupled to a B&S flathead prime mover.

Go figure!

My whole reasoning behind using a generator was actually prompted from the diesel electric Locomotives. If you look at the standard generators out the they are running at around o.33 gallons an hour at 80% load, and if you can run an electric motor off that generator at 60 miles and hour only using the 80% load from the generator wouldn't that work out to 180 miles per gallon give or take depending on driving?

I know the engineers who came up with that idea have to be right. I believe this is done because the electric motors have 5 times the torque which is necessary to get something as heavy as a train moving effciently. You have to wonder if you can relate this to cars producing their own electricity for that reason.

I think you'll find you'll need a large generator to provide the power you'll need particularly for acceleration (maybe one in the 40kw range.) Without a means to store the surplus energy generated, the direct drive would require the generator speed to be constantly modulated to avoid inefficiency.

Check out the GM Volt: http://gm-volt.com/about/

Until I see it working "reliably" in person I still see it as a concept, but it sure is a step in the right direction. It's an electric vehicle with on board generator, sort of what you are proposing but with a 16kwh on board battery.

Without a means to store the surplus energy generated...

Actually, the Opel has a battery bank, too. It was described as "heavy duty" car batteries, so 80 Ah is probably close. So the battery bank would be about 3.8 kWh, adequate for 30 kW bursts. The Volt is intended to have useful range on grid power -- thus the large battery pack (as compared to the 1.8 kWh Prius battery pack). But for the Opel the 3.8kWh is probably pretty close. 50 mph continuous seems a bit optimistic, and the 5 hp a little too small, but otherwise, I think the design could work pretty well, provided one avoided long hard pulls.

Any onboard batteries could help provide the 'boost' needed to get the vehicle moving and accelerated. As long as the generator can generate faster than the parasitic loss to aerodynamcis and rolling resistance then the car should drive fine. From a air drag perspective a reasonably aerodynamic car only needs about 30HP of power to overcome the airflow at 60mph...so a 35-40hp generator should do the trick with the help of some batteries to acceleratre. The reality of this kind of a setup is that if you drive into a headwind (or up a hill) your generator isn't sufficient and you'll either be travelling at a reduced speed or stopping periodically (and for quite a while) to let your depleted batteries catch up. I grew up in southern Alberta and hurricane force winds are not at all uncommon...driving back home into these gales would make my little 1/4ton toyota truck strain like it was towing a trailer of elephants...not the place I would venture in an electric car if I had any hope of being home for supper...

kkjensen,

A 40hp. generator is nearly 30KW. That's probably half as big as your car.

j.

I know! :P Very much the reason I'm not planning on putting one in my car! If I do anything along these lines (having an onboard generator) it wouldn't be with an AC generator because then we're just introducing even more conversions to get the generated power converted to DC to drive my motor and the excess converted to something battery friendly to top up the batteries during the trip.

I've heard about and read about some turbines that could output the needed power. However I don't think doubling the size of the car is that practical...neither is doubling the weight (no lead acid batteries for me) ...until I see some working examples I'm not going to start throwing my lunch money into someone's stock.

For me, for now, pure electric is what will drive me to work sometime. Anything longer than that is generally a family affair and we take the minivan...and we won't get into efficiency about that brick on wheels...

If I do anything along these lines (having an onboard generator) it wouldn't be with an AC generator because then we're just introducing even more conversions to get the generated power converted to DC to drive my motor and the excess converted to something battery friendly to top up the batteries during the trip.

If you really do something along these lines, then take a close look at AC generators. A typical car alternator is a three phase AC generator, with built in diodes and voltage regulator. The typical car alternator is not particularly efficient in comparison with other electric machines, but it is more efficient than the typical old DC generator used in cars. In practice, high efficiency dc brushless motors (which are effectively ac motors with permanent magnets and controllers which convert DC to approximate AC) are just as efficient (if not more so) as high efficiency brushed DC motors of the same overall specs. A big advantage of the AC or brushless DC approach is the lack of brushes. So, to make a long story short, the all the AC-DC and DC-AC conversions are pretty efficient, and, if anything there is probably a slight advantage to using AC (and brushless DC) motors. Thus when you pull out the stops and ignore cost (as in the Tesla) you find AC motors, and production hybrids also use AC motors.

Your basic notion of avoiding conversions is, of course, spot on -- its just that nowadays these conversions can be efficient enough that other issues may tip the balance in favor of doing more of them rather than fewer.

Thanks for the info. Is there an 'off-the-shelf' and not too pricy way of getting from AC to DC? I'm more familiar with mechanics and smaller scale, digital types of electronics...not the big current, big voltage, industrial kind of stuff that generally isn't found in DIY work (at least not in my garage!).

I'm just in the process of converting an old eagle talon to electric. Gas hit $1.50/L (~$6/Gal) in Montreal the other day. I'm sure it won't be the prettiest or most graceful electric vehicle out there but the hydro power here in Quebec is so cheap it just makes sense. I'm only looking at a <50km round-trip commute to work every day so I don't think I'll be worrying about generators anytime soon. Do you keep any sort of blog or webpage for your vehicle there in your avatar?

what you're looking for would be is a bridge rectifier; available in both single & 3Ø.

last one i bought, paid ~$6 US for.

I really don't think RWS that you are paying attention to what you write.

What "standard generator[s]," i.e., voltage, max amperage runs on .33 gallons an hour at 80% load????

Everything else that you write is pure air until you specify real numbers for that generator.

Then I would bet it would still be air although then not so pure.

j.

The best way might be to start with a plug-in electric vehicle that can go about 50 miles at 35 mph. They are not too expensive and you only have to decide on what battery you want to use, heavy,big and cheap or expensive, light and small. To go faster shortens your range, as does having AC, heat and power steering/brakes.

A 20 kw generator will easily power a full size car by recharging the batteries as needed. A generator can be run at a very steady output and speed allowing your engine to run at its most efficient speed. Then you have to decide what engine to use. Internal combustion engines inherently produce pollutants which require power-using pollution controls and they are all basically built to run on a petroleum product. Sure, you can scrounge used cooking oil or try to run a still [very secretly to avoid the law] to make your own ethanol. Fresh vegetable oil or pure ethanol is scarce to expensive. External combustion engines produce less pollution than the best IC engines and can use any liquid or gaseous fuel.

So drive your generator with a steam engine, one of the new compact and lightweight designs. [See Cyclone Engines, Lynx Steam engines, the Green Steam Engine and the Tesla Turbine. Some assembly may be required.] Your car will be quiet and clean, have the range of a standard car and use about 80% less fuel as most of your driving will be as an EV. Call it a steam-electric hybrid or a steam-electric extended range EV or whatever you want. It sounds very doable to me, providing you have the money and technical skills to build it.

Contact beesidemeusa@yahoo.co.uk by e-mail and ask about steam-electric vehicles to get more info. He has a lot.

Yes, you can! In fact, it is more efficient than a gas powered car because the generator runs at a constant RPM where the engine reaches maximum efficiency and then charges batteries, which drive the car's electric motor, which drive the wheels.

If you are interested in learning more, there are a number of companies that sell the components to convert a gasoline powered car to electric. A friend did just that to a Toyota MR2 recently.

Well done conversions can be 1/5th the cost per mile to drive than gasoline. There are limits like total range between recharging, but if you are looking at daily commutes under 20 - 40 miles you can realistically hit those targets.

Just do an internet search for EV DIY and you will see a host of information on the subject.