Power problem

Small backup generators are readily available, and can be connected to the house in various ways to provide a basic level of electrical supply. Off-grid solutions are mainly based around collecting dilute energies and concentrating them for storage, and there is a wealth of information on the 'net.

Stand-alone heating sources can be as basic as a firewood stove that <power cut>

Hi Conrad - Also struck by darkness sharing?

Nothing is readily available at present. The don't even sell 7-10 kg LP gas cylinders separately at the moment.

Hi Hendrik. Yes, it is driving me crazy. I have now been out 3 nights in a row apart from all the previous times. My other problem is that the trip switch, supplying our block of houses, is under rated in the street sub, so the slighttest anything on the overheads trips this breaker. And to get a person out to come and flip the switch can take 2 days.

I have no suggestion for the breaker. However If you want to go to batteries then alternaters on cars can generate up to about 125 volts DC if the regulator is rewired properly. Most car alternaters can generate 450 watts or more at 12 volts and more as the voltage goes up. 5,000 to 6,000 watts at 125 volts. Ham radio operaters use this setup regulary in the U.S. All you need to do is find something to pull it. water wheel, steam engine, gas engine, or even human on bicycle.

Hello Guest!

Which makes of alternators do you use to get 125V? Best I could ever achieve was 100V with winding open circuit. As soon as I placed a load on it the voltage collapsed. Obviously the wrong brand/model. But which is better?

I would question the 5000 or 6000 watts from an ordinary automotive type alternator as a sustained output for hours or days.

I have such units designed for that kind of service at lower voltages and they are nothing like the dinky alternators you get as OEM equipment. Battery charging and in particular driving an inverter will rapidly overheat a light weight unit.

What do the hams use for a speed up gear box when using a water wheel or steam engine? These power sources typically turn at very slow speed compared to a regular automobiles. Ordinary automotive alternators do not produce their full output unless the rotor spins at least 4000 RPM and faster on the smaller frame units on late model cars. So a speed up gear box is definitely required.

Hello elnav

When I was reading the post by the guest, I was wondering about the ham radio operators also.
Years ago before the advent of cheap inverters and good battery power tools, there was a device available to connect to your alternator, and mount on the firewall that had a regular 110 V outlet to plug into. I never used one, the manufacturers claimed you could easily get 110 V DC out of the setup, I believe they stated that most drill motors with brushes would run on DC.

I was somewhat annoyed with your post on battery charging. Some time ago I read an article about a battery powered boat, that explained how to bulk phase charge its batteries. Needless to say while I was working on a post explaining the hot tips for battery charging ,you posted. Great post! I picked up a few new pointers from it. I didn't see desulfation battery chargers mentioned, curious if you had any experience with them.

Just a question of curiosity. At one time I had thought about bypassing the diodes in a alternator, that should've left me with three phase AC, never got around to doing that either. Have you ever seen or done anything like that?

Very interesting post, especially about de-sulfation using electronic techniques. I do not have the exposure to the number of batteries to find out for myself......Many thanks.

Andy, I would be very surprised if there isn't an equivalent product in Europe (Germany) or perhaps an importer of the actual Pulsetech product. If you have any seasonal equipment that gets stored for several monthsof non use, you are a candidate for usign this technology. As for getting used batteries, I should think you can pick them up at any caravan dealeship. This is an especially frequent application which suferes sulfated batteries.

I've got good batteries, I design and build my own chargers, I also include a "Battery Zapper" in the charger that I stole the specs from elsewhere, I have no problems with sulfation either (at least up to now!), its just that I am not exposed to the number of batteries that you are to test out on!!!

You brought the "experience" that I was looking for, many thanks. I now know that they really do work!!!

This is wrong to my understanding- Watts = volts x Amps- there is no free energy- a human would be struggling to produce 100 W of power- the only free energy is Sun, wind, tidal, wave, geothermal, waterfall, stream- & gravity(not to mention zero point energy, atom energy, chemical energy,& of course radioactive materials).

Don't forget piezoelectric and of course dilithium, that's gotta be a biggie.

A quick question, have you ever tried to run a refrigerator off a computer UPS. I have no doubt that it could be done however I'm not sure you're taking the starting load of the compressor into consideration.

A typical household refrigerator has a one third horsepower compressor or when all is said and done about 300 W running. Which a computer UPS could supply, however the initial starting surge is somewhere around five times that, and that's probably conservative. I have managed to start completely unloaded compressors with a generator slightly less than four times the running load, and that was sketchy ,in that sometimes the compressor would start sometimes a circuit breakers would pop. I've never tried to start a relatively large inductive load off a inverter. A generator has a lot of things going for it that makes it forgiving of a momentary overload, I would think an inverter would be much more sensitive. Also assuming a 12 V 100 amp hour battery you're looking at about three hours continuous run time, and that's just to guesstimate the actual draw for 300 W is 25 amps however that is not taking in the inefficiency of the inverter. Just curious actually it had never occurred to me to try running a refrigerator off an inverter ( not too many years back a large inverter would've cost more than a refrigerator). Inverter prices have come down. A 1500 W inverter might start a refrigerator, I may go inverter shopping just have another project I don't need.

Modern inverters can handle a short 5 second peak load 2X the normal continuous rating. The newer designs using toroidal transformes and high speed switching frequency, can handle up to 3X the continuous rating, for about 5 seconds.

To improve the peak demand response keep the cables very short and over size them as much as possible. It also helps if you keep the battery voltage up to float level by supplying the batery with a charign source liek an alternator. If the inverter design allows it, adjust the output voltage to near maximum of the normal range. This minimizes the draw from the refrigerator.

These days running fridges and even air conditioners on inverters is fairly routine. Of course this assumes the sysem was designed and built properly to begin with.

Hello Elnav.... thank you for the information. I have about a 10-year-old 400 W inverter that didn't seem to get along with the inductive load of a battery charger. To shorten a long story a 25 foot extension cord and a small battery charger would go were the jumper cables would not. The scheme worked but not very well I could tell I had a low-voltage situation at the battery charger.

I just saw a 1000 W inverter on sale. Which I now intend to go purchase, so I can prove you wrong, or least that's what I'm going to tell my wife. She might except that better than me buying a 1000 watt inverter for a infrequent power failure, which rarely lasts long enough to cause a problem with food storage.

So I don't have to do a separate post I decided mention to the original poster, that if he decides to go with an inverter (which it seems I was overly pessimistic about a inverter's ability to withstand large inrush currents) battery scheme he could build a 100 amp 12 V battery charger for probably less than $100 US. All that's needed is a 5 hp lawnmower engine, and the alternator and regulator out of a police car, in fact nowadays there is probably a lot of vehicles in the wrecking yard that have 100 amp alternator's an integral regulators. I know it works I built one to Charge batteries at the track. That would give you less than 1200 W continuous power but it certainly would run the refrigerator, some lighting and a TV set.

+When the load and the battery are separated by any distance place the inverter next to the battery and run a long extension cord for the 120V. Rule of thumb. Make DC cables short, AC cables long.

Someone mentioned about plugging an inverter into the cigarette lighter socket. That is probably the worst thing you can do. Neither the plug, socket or car wiring is designed to run an inverter. Too much resistance. Cut the inverter AC molded wires short and replace with #10 or #8 Gauge wire, which you hard wire to the battery terminal with a suitable fuse in series.. You will see an improvement. The inverter will run slightly cooler and it will take longer before you reach "low battery V " status.

Concerning the 100A 12V scrap yard charger. Yep! works like a charm. I was involved in building my first such charger back when I was 14 years old. If you plan to run that kind of setup for hours on end at full 100A output, I highly recommend doing something to improve the alternator cooling.

For better results try and find a "constant current" regulator. You are most likely to find these on Leece-Nevile alternators fitted to Ambulances and fire trucks. Older L-N alternators had their regulators fited to an external pocket near the brush holder assembly making it easy to upgrade to an external regulator of a diferent kind.

'80 and early '90s Ford trucks with MOTOCRAFT alternators are also a good bet since they also have external regs. However they are not as rugged as L-N units.

On some VW Diesel cars, you have a 120 amp alternator....some trucks use 12 volts and have heavier alternators than that.

A search with Google showed Truck alternators upto 5 kw......but expensive.....there are some re-worked ones that fall somewhere in the middle....

I like your idea with the lawnmower motor!!! Direct drive or V-belt?

Hello Andy
I build this contraption about 20 years ago using a 100 amp alternator off an old Dodge police car, and a 3 hp Briggs & Stratton. The one I built was belt driven, there was a problem with the belt drive as the alternator was spinning backwards. Electrically the alternator worked fine in reverse rotation, however the cooling fan was running backwards.

I had several potential uses for the device in mind such as charging the battery on my RV ,when I was away from develop facilities, and providing a quick recharge or some extra cranking power for finicky racecars. The only real use it got was doing a quick charges or jumpstarts, so cooling was not a problem. I had intended to mount a supplementary fan for cooling, or a jack shaft on the frame to correct the rotation problem, however never got around to it.

It was a pretty neat device, very portable, reasonably light, cheap and easy to build, with far more 12 V output than most of the small generators available at the time.
In case anybody ever decides to build one, on paper the 3 hp Briggs & Stratton should've been able to do the job, in reality I ended up under driving the alternator and could not quite reach the full 100 amp output without bogging down the engine.

I elected to use an alternator with a remote regulator. By attaching a battery pack (3 V I think it's been a long time) and bypassing the regulator I was able to excite the field enough to start a charge on a completely dead battery. I had intended to add a rheostat to give me a variable DC output capability. Never quite got around that either. For some reason it finally popped in my head that this might be of some use in solving Conrades problem.

Cheap down and dirty, and not nearly as pretty as a store-bought generator but it will work. We used to have a cartoon hanging in the shop captioned" I've done so much, with so little, for so long, I can now do anything with nothing at all", which was good for a laugh as we were always short of time material and equipment. The experience must've twisted me, cheap down and dirty has always been more fun.

P.S I believe lead acid batteries are intrinsically safe to work with, provided very basic safety precautions are taken, which have already been mentioned. Personally I've incorrectly assumed that someone was familiar with the most rudimentary of safety procedures, and ended up being wrong and narrowly avoiding injury. So go ahead and harp safety, the worst that can happen is a little eyestrain from reading the posts, which is far better than the alternative.

Lost the last part of the post while editing. Elnav hit the nail on the head. when you work with hazardous materials in hazardous conditions thinking about consequences or hazards become second nature and a simple battery seems pretty trivial. You assume any one knows that. Of course you assume every time someone takes a cutting torch to the gas tank, or to an unexploded artillery shell that they should've known that they would get killed. There've been a lot of Darwin awards, and they're always presented posthumously.

PS forgot to check the off topic box and the edit function will not allow me to sorry.

YMROADRUNNER wrote: there was a problem with the belt drive as the alternator was spinning backwards. Electrically the alternator worked fine in reverse rotation, however the cooling fan was running backwards.

REPLY: Roadrunner probably already knows this, but more recent models of alternators now have cooling fans that can run in either direction. Balmar, one manufacturer of custom alternators, performed a test to demonstrate the difference between one direction and the other. The measured difference in cooling air flow was 1%. Look for fins that are perfectly radial in alignment. Fan blades which are angled must be rotated only in one direction.

Something else which eludes many people trying to build such a portable engine driven battery charger, relates to rotor speed. These alternators must reach a high RPM to deliver full output. Most ordinary automotive alternators require a rotor speed of at least 2000 RPM to put out any substantial current. Maximum output occurs above 5000 RPM on the rotor. Small utility engines typically do not exceed 3000 RPM. Therefore you need to have a 2:1 pulley ratio in order to produce the full rated output.

Automotive engines on the other hand often have a normal safe RPM of 5500 RPM crankshaft speed, and race cars or sports cars often have a red line that is much higher. In such cars the alternator can be spinning at 10,000 RPM or more. Balmar makes one that is certified for 15,000 RPM.

Lastly; in my work we use a rule of thumb that each 100A output absorbs 5HP. I usually work with systems requiring 150A - 300 Amps at either 12V or 24V. We use special regulators that can be programmed to unload the alternator while the engine starts up, or fine tune the output to prevent stalling tiny engines such as is used on sailboats. I have seen shafts sheared off when the alternator was turned fully on abruptly.

Elnav

Hi elnav

I'm making the assumption that the bidirectional fans are only on late models with serpentine belts. This is the only way I can figure the direction of rotation changing ,since automotive engines that I'm aware of all rotate the same direction. You seem to be quite up to date on the subject, I haven't worked with this for 20 years. Do serpentine pulleys exist that fit the crankshaft of a small utility engine, short belts? Or is a solution to this problem changing the pulley on the alternator .

I originally use the following figures to select the engine. 3 hp approximately equals 2250 Watt's. 100 amps at 12.5 V equals 1250 Watt. I assumed a 1000 W cushion would be sufficient to cover belt losses and resistive losses in the alternator, However empirical data trumps paper theory every time, (since then I've doubled my Murphy factor for anything I'm not sure of) Hence the best performance was achieved with about a .8 Under Drive, I believe my handheld Tach indicated 3600 crankshaft rpm. It appears my 5 hp guesstimate stated in a previous post is pretty close to what you observed in real-world conditions.

The only point of contention here is your maximum RPM for an alternator. I had to go raise a hood on my avatar but a quick measurement yields a 23/4 inch pulley diameter on the alternator, 6 1/2 inch pulley diameter on the crankshaft. A ratio of 2.36 to 1.
Throughout the years I was actively dragracing Maximum RPM and shift points varied, Depending on the engine and configuration, a 7000 rpm shift point has been routine in the past. If I have figured the ratio and rpm right, 16,545 rpm is what the alternator would be spinning and at 7000 crankshaft rpm. There are small block Chevy's running around out there that are spun much tighter. There certainly must be an upper limit as far as the rpm a alternator can handle , however I've never experienced a rpm related alternator failure. I can attest (if I've done my math right) to having spun a alternator in excess of 23,000 rpm, do to a transmission failure, I wish the engine had fared as well as the alternator.

Bi-directional fans began showing up about 10 years ago to the best of my knowledge. It probably was the advent of serpentine belts that encouraged this. In boats we often have to mount the alternators backwards beause there is no other way. Pictuer if you can, a 90 Amp alternator mounted onthe nose of a 2000 HP boat engine. This is what is used to charge the start battery.For the house battery we use a 200 or 300 Amp unit which is completely separae from the start battery system. We also sometimes end up with different voltages like 24V start and a 12V house bank.

Balmar uses Leece-Neville frames and more recently Prestolite but spec larger shaft diameters and heavier duty main bearings. They also replace the sleeve bearing in the tail with needle rollers. In addition they have the stator wound with larger gage wire in a configuration that produces almost 80% output at near idle speed. Large frame units are better for that. but not as fast.

I have not seen serpentine belts used on small utility engines but companies like GATES do make "cogged" belts or serpentine style ribbed belts for power transmission applications. They do have short belts as well as the longer belts common on cars. I would be more inclined to just put a Vee belt on the alternator.

In general 2.9" diameter is used for Vee belts but if the ratio isn't enough you can go to 2.7" diameter and get a bit more speed. Unfortunately this also creates more flex and thus heat in the belt. On bigger diesels which never turn past 2400 you often have to go with 8" or even 10" crank pulley size to get the desired alternator output. I once had to use a jack shaft to get the speed multiplier necessary. These engines are normally run at 1200 RPM cruising.

My own truck diesel runs 1300 RPM at the highway speed limit. i have never had mine over 2000 RPM even though the governor is supposed to let it run to 2400. Big boat diesels may top out at 1500 RPM.

Most of the alternator output curves I have seen show a decline once you get past the 5000 - 6000 RPM point. Its like the power curve on a motor. Beyond a certain point, its a case of diminishing returns.

Centrifugal forces on an alternator can bend the fingers outward if they are not real solid pole pieces. Sometimes you end up shaving the tips where they touch the stator pole pieces, but once you slow down again the contact noise disappears. Unless you checked you might never notice the difference except for slightly lower output at idling speed. lets face it who in racing circles bother with doing many checks at idling speeds. Its top end that counts in drag racing.

Most of the major rebuild shops can supply alternator pulleys of various diameters. Shaft size is fairly standadized to a few diameters.

While its true an alternator might be spun much faster than 7000 or even 15,000 RPM its a case of useless rotation. Drag racing only last a few seconds per run. Even circle track racing only last a fe hours. Unless the whole alternator is designed to run at very high speeds with the correct number of pole pieces, it doesn't work well. The standad number of pole pieces will produce such a high frequency AC signal to the rectifier diodes that the whole assembly drops output drastically. you can machine the stator and rotor pieces to give clerance at very high revs, but then you loose output at the low end.

The tiny 100A Balmar unit guaranteed for 15,000 RPM is specifically designed as a drop in replacement for racing boats using Mercruiser or similar automotive blocks that have been marinized and blue printed for racing.

My own personal favourite is the VLF series designed for train locomotive use. 300 amp at 27.6V or roughly 8000 watts continuous power. It takes almost 20 HP to run. Reason for the losses in addition to those you already mentioned; is power factor which screws up your conversion calculations.

The former director of engineering for Balmar happens to be a personal friend of mine. As a result, I have a lot more insight into that brand than the other good brands on the market. however most of them have similar characteristics. So the theory is equally applicable.

For anyone contemplating making a small DC genset, consider any of the Leece-Neville models that have the regulator mounted in a bulge on the rear outside. Thes alternators have an isolated frame and you can easily convert the normal alternator into what's called a constant current model. These will charge up a battery a lot faster than the regular automotive types. you will find these on Fire trucks, ambulances, and sometimes police cars and even heavy duty taxis. The reason being these vehicles spend lots of time idling but also have large electrical loads.

In addition they have extra cooling for running at slow speed near ful lload. Perfect for driving an inverter.

Any good alternator shop should be able to supply a fan for the right rotation regardless which way you mount the alternator.

Highway coaches sometimess drive a second alternator from a PTO on the transmission. There was a time when most coaches like MCI had dual voltage systems. Part 24V and part 12V. Boy were they fun to work on!

Nice post and a good "Cheap" Generator.

I must hone up on my welding skills and get one made up for camping, if I can find a really quiet motor, probably from a Honda lawnmower or similar!!!

Thanks Andy
Replacing the noisy 3 hp Briggs & Stratton with a 5 hp Honda or similar engine should make for practical power source that won't rattle the windows of your RV.

Hi,

To solve your power problems you can install a solar power system which consist a solar panal and inverator type setup which charge the battery in day time and suplly electricity in night.

Sanjeev Kumar (sanj_kkr@yahoo.co.in)

I don't know of any of this will be of any help however, at least in the United States large inverters are inexpensive, of course there are many generators available in the 3000 to 4000 W range for between 300 and $400 US. I don't know if you can mail-order anything from out of country suppliers. If you should happen to come up with a US standard generator that is a 120 V/208 volt 60 Hz unit the lightbulbs won't care about being run on 208 at 60 Hz. Many of the air conditioning compressors that I work with are rated for both 50 or 60 Hz, I personally wouldn't be too concerned about running the refrigerator at 60 Hz however there is a good possibility that you can adjust the frequency of a nonstandard generator.

A bunch of lead acid batteries and a large inverter recharging off the grid when it is on would certainly solve your lighting problem. As far as the refrigerator ,the starting load would probably be too much for most inverters to handle. I would keep the refrigerator full of liquids i.e. bottled water soda whatever and as long as you kept the door closed the thermal flywheel effect would preserve things for a quite a time.

What is a geyser? How much power does it require. LED lights do not require very much power so can run a long time on even a car battery. Being a common item sold for Caravans and boats they should be available but perhaps the price is unreasonable. Sealed lead acif often called GEl or AGM ( two diferent types) are suitabel for deep cycling.

A geyser is for hot water. It stores about 150L and the element cycles to keep hot. It is set to about 55 deg C and reguires about 3000W when on. I am not concerned about it being powered when the electricity is off. It will make my solution to expensive. I really just need lights and maybe a tv. Power is usually off for about 3 hrs but sometimes right through the night. It feels like the dark ages. :)

A Geyser is a water heater. It runs on gas best, do not use electricity......Gas can also power refrigerators (of the right type!) Then power outages can be less of a drag....

Batteries are good for LED lighting, do not use halogen, they need too much power!!

Thanks everyone so far for their comments. I have some ideas now. Please add more comments if you have better ideas as they all count.

Personally, I would be fearful about ordering a portable generator; probably because you would pay for it and never see it. After our rash of hurricanes back in 2003, folks would buy generators online/mail order and they would disappear in transit. If what you want is also wanted by lots of other folks, money talks and there goes your generator. Trust is overated. I don't lie and I'm always right.

You said "I don't lie and I'm always right." You are far too modest.....!!!

...they should be sane enough to allow teasing!!

maybe this would be a good test before hiring anyone!!

If you have gas in the house, there are gas powered refrigerators, and I would look into getting an older stove that does not require electric power for ignition (as most modern pilotless ones now do). I bought a new stove a few years ago and specifically asked if the gas valves could be used without the igniter, and it can on this one so it is possible on newer stoves, but you have to ask. I also have a gas water heater and gas fireplace, although the fireplace would not be capable of heating the entire house without serious modification.

I feel that if there is no chance of the situation being improved, you need to do a couple of things:

1) Decide what you need in an emergency and what you do not need.

2) Add all the wattages and find out how big an emergency generator you need to supply your needs. Double the size at least of the generator, never have one running on its limit.

3) Have your distribution panel marked clearly with paint to show which breakers should be left on and which must be switched off.

4) Have a changeover switch installed that ONLY supplies the needed breakers.

5) If you take a Charging unit that is made in Australia (sorry, forgotten the name!), it is almost silent and the exhaust heat heats the water for you as well!!

6) With an automatic switch over and start of the generator, you do not need to do anything!!!

we have similar problem in India. i use gas for stoves and geysers.gas fired geysers are available in India,and use battery back up for lighting,TV and fans we restrict our selves on battery back up by reducing loads to conserve battery power .you can get a battery back up of 6to 8 hours.i don't know the cost of gas in SA and availability if gas is cheap you can use gas fired absorption chillers for Air conditioning number of makes are available even gas fired refrigerators are available.which you will find in many star hotel rooms.

crm

Change the goverment!

Otherwise get a rite size backup generator as they normally do.

(Consider a renewable type if you wanna be environmentally friendly!)

Here in the Dom. Rep. we have the same problem, daily power outages of 4-12 hours.

I run a 1.5k inverter with 6 6v deep cycle batteries. This runs all the lights (low consumption fluorescent) 3 computers tv etc. gas stove.using the correct batteries for the inverter is important as they can take the constant charge/discharge cycles.

Trace/xantrex inverters are a well made brand and available up to 3.5k and are stackable. It's worth the money to get a brand name that will last, The power will not get better!

We manufacture our own low cost inverter down here in 800w & 1k with a 45amp charger and is available to our employees al cost and company financed.

I could never survive without one!

By the way,There are many people here that make homemade inverters in thier house to sell. Plans are all over the internet. You could have a nice income from this!

Replace your shingles with solar panels to keep your fridge running and produce hot water by installing serpentines below the solar panels. The solar panels should also charge batteries for electricity needs at night. Also install a wind energy propellers as a backup. Collect all human waste in a pit and produce methane gas for cooking.

It does need some capital to install the above equipment but once you've installed it you'll enjoy it.

I am not sure that I will "enjoy" the bit about human waste!!!!

Andy i India cow dung is used to produce methane many large kitchens which feed 3to 5000 meals a day is run on this gas used for cooking i suppose you can give a try.

crm

...I was trying to be funny, sorry if I missed my mark.....

In Germany we have such systems supplying 20 or more houses with heat and electricity 24 x 7....all the year round.....I knew they worked....

I don't think my neighbours would like the idea either

You hit the nail right on the head!! Healthy but smelly!!

its time to go green we can offer a solution where you can go off grid and have the power you need battery bank with a sunny island and our charge heads 0 Fuel 0 emissions

http://www.magnacoaster.com

cost is looking to be $2.00 a watt

Your web site looks like a con. No explanation no pictures, no diagrams. Only a complete idiot would order one on the info you supply!!!!

You need a new marketing manager to make sure that it sells.....

For household use and short outages, nothing beats the small generator both for price and convenient.

Buy one with electric start, Install a changeover switch or if you are really want to go sophisticated, make an auto transfer switch. I know you know all this, just think that in your case I wouldn't go crazy about latest technologies and smart gadgets...

Last time I was in the RSA, (1983) it was so nice...I loved it than.

Wangito.

I will do that. I am currently working on some ideas and are awaiting for some reply's. It looks like i will go the battery, inverter, charger route though. Also i will just power some lights, tv. Other high current appliances like stoves, geyser ect.. will have to wait. It will get too expensive. But i will keep everyone up to date as soon as i have the answer. Thx anyway. And yes it seems we are going backwards with great speed in SA (my opinion). Some will agree, some not. Depends who you are.

I knew SA in the "bad days" of Apartheid, but you were safe on the street......

I have visited several times over the last 10 years, the last time must be 3 years ago, on none of these visits did I leave the hotel at night, except with friends.....the friends always had guns in their cars for "incidents", some had machine guns.....!! That is worse than the old "Wild West".....

Too damn dangerous.....and a beautiful country that is getting completely screwed up by the population there.....

A point not mentioned in the case of engine powered alternators/generators- usually the engine is fan assisted cowling cooled-ie "air cooled"- this type of engine needs regular oil change- sometimes as frequent as 50 hours run time- ignore this , & your electronic loads may burn out- literally- as the carboned up engine "hunts" in an effort to answer regulation/load requirements- usually overvoltage spikes that burn movs etc (if fitted!).

As engineers we are always talking about "Well designed system"

I.E: sufficient power capabilities to avoid "Hunting", together with good regulation, and of course, preventive maintenance. when all this is done you will most likely have a good emergency system. 50 hours as far as our poster is concerned are 15 to 20 power outages. not likely to happened over a very short time. And if they do, he already has his alternative planned.

Wangito.

I'll try and put some points to you that make sense:-

You wrote:-

I have seen plenty of engines where the recommended sevice interval was exceeded without getting the aforementioned Carboning up problem.

If a "better" oil is used, then this time can be extended considerably, even if a filter is not used. I personally recommend only Synthetic due to its better properties and life time.

My question therefore is: what is it about air cooled engines that causes them to carbon up more so that other engines?

Mostly, but not always, air cooled engines are 2 stroke and burn oil with the petrol, this causes them to carbon up quicker than a 4 stroke. Especially if only run for a short time, or the owner thinks he is doing his engine a favour and adds too much oil to the 2 stroke mixture.

All aircooled engines have greater gaps/tolerances than a water cooled engine as the water cooled engine has a smaller temperature range to run in......whereas air cooled engines run at a different temperature in summer than winter even at the same load. This must be accounted for when designing/building such motors....

Andy wrote:

All aircooled engines have greater gaps/tolerances than a water cooled engine as the water cooled engine has a smaller temperature range to run in......whereas air cooled engines run at a different temperature in summer than winter even at the same load. This must be accounted for when designing/building such motors....

REPLY

Oh right ! Forgot that from my long ago VolksWagon days. Come to think of it, Deutz tractor engines have the same issues. however running the engines close to ful lload and geting the engine right up to operating temp helps minimize fouling and cylinter head deposits.

Locally I haven't seen much in the way of 2 cycle engines except for outboards engines. Most small pumps and generator engines are 4 cycle. This might be related to the fact 2 cycle engines are being outlawed by the EPA.

Victron has a very intersting generator test report available on their website. Wha tcaught my eye is the fact the Brake Specific fuel Consumption is lowest as the generator runs at peak load. Its a curve but you can see the peak section quite clearly.

That tells me a properly matched DC genset designed to charge a battery house bank is far more efficienct than a conventional AC genset feeding AC power with greatly varying loads. Run time to charge the battery bank will be shorter because most battery chargers ruuning on hoousehold current are smaller than the 100 - 150 amp output available from a truck altenator driven by a small utility engine. Fuel consumption would be less since the only time the engine is running is to charger the battery bank. Such a purpose built batery charger engine is usually sized smaller than a more general purpose generator package. Inverters can handle start surges greater than their normal ful loutput rating.

I know of several house holds that run quite well on a 3000 watt inverter but in most cases it would take a 6 or even 8kW AC genset to power that same house hold. The reason being the generator cannot handle big surges to start motors. Its interesting to note that the Honda inverter series of gensets do have a limited ability to handle a surge because they incorporate an inverter in the design.

Since I don't know what the cost of the generators is in your country or what you consider expensive I thought I'd send you a link to look at some prices. I'm sure most of these generators are shipped direct from China possibly ,you can figure out some way to get them into the country may be you can start a business. As others have mentioned sizing is only a guess until you know the load. If You have electric heat electric hot water heater or an electric range, you've got problems if you can't switch over to natural gas or propane. If your only concerned with the lighting and the refrigerator and miscellaneous small appliances 3500 W would be more than adequate to start the refrigerator once running its demand is much smaller. If you're stuck with an all electric appliances (as I am, was a pain when we had rolling brownouts) I would try to double that figure and live with the fact that I can only use one power hogging appliance at a time, even if you have 8000 W available you may not be able to run resistive heat appliances at full capacity.

http://www.bizrate.com/powertools/products__keyword--generator__lp--1__sfsk--2.html

There have been some very good solutions proposed, safe practical and convenient. However we sometimes forget ,while we can run down to the local supply house in five minutes and get just about anything we want immediately at a competitive price this is not necessarily the situation in every country, or indeed every part of the United States, with the advent of the Internet however getting parts shipped to the boondoggles has become a lot easier.

So my opinion, go with a small generator (but the largest you can practically afford) electric start would be great, but pulling the rope and flipping a manual transfer switch, living with the fact that you may not be able to run all your appliances at once would be a cheap effective and practical solution, of course if you can afford it the fully automated systems would be a much better solution.

You find an excellent on-demand gas fired hot water provider under:

www.foreverhotwater.com it takes 3kW of your load for a starter.

The thread is excellent, and I dont care what load you want to feed from inverter / generator. After all it is a tradeoff.

BUT, I want to emphasize in all capital letters: USE ONLY PROFESSIONAL TRANSFER SWITCH WITH A SUBPANEL properly labeled for your installation, manual or automatic flavor, your choice. It is a foolproof (childproof, family member proof etc...)switchover. It wont blow your generator on mains power return as a bonus. Just as important the fire department, building inspectors accept it, and it will not void your home's insurance. Viewed from such an angle it is cheap insurance indeed.

I have given this a "Good Answer" rating...

Hi andy

You can through more light on this how about rebuilding or reusing old Volkswagen engine couple it to an alternator and run as generator off course it has to be enclosed in a acoustic enclosure .i remember we had done it for fun during my training days at engineering training base to kill time.here i have seen truck engines used as prime movers for generators.exhaust emissions can be handled with out much problems

crm

I hate to throw a "damper" on your enthusiasm, but you may have picked just about the worst motor there is to pick, sorry...

Why? you may ask!! And I am sure my list will not be complete!!!

1) Engine is air cooled, so using up the heat of combustion for warming the house will be more complicated (due to noise pollution alone) than a water cooled engine would be.

2) The engine is very old design wise (before WWII) and as such inefficient, loud, short lived and polluting. It does not even have a proper oil filter!! It relies on a sieve construction!! It is not even allowed to use Synthetic oils, which means frequent oil changes and a lot more old oil having to be handled somehow in the environment.....

3) It is a strange shape, (a flat 4 cylinder) so it takes up a lot more space than a conventional engine.

4) Has a carburettor, so controlling the air to fuel mixture from an Oxy sensor and a catalytic converter are quite difficult to organize....

5) It is only around 55BHP in spite of being around 1.5 liters in capacity....and that was only the later engines. Earlier ones had even less power....

There are plenty of smaller engines (with 40 to 60 BHP) that would be:- a) cleaner b) provide enough power around, with Cat etc... just waiting to be picked up at the scrapyard.

I know you meant well and that your comments were also friendly, but I still felt that you should know and understand the true facts! Have a great day in spite of my negative comments.

Thank you sir i undertook this adventure or misadventure in 1971.Thanks once again for updating about Volkswagen engine.

crm

I suspect that in 1971 I would have been far more enthusiastic about that motor!!! Its amazing how ones ideas change with time!!!

Have a great day!

If generators are expensive in South Africa can u not import one directly?How is the duty structure?The option is to use UPS which is battery backed device .This may be sufficient to have the lights and may be the fans .Atleast you will supper with lights on.Ac May not be operable.Now a days solar backed UPS is available which will charge the battery during day time if u have bright sun shine or whenever power is available your UPS battery will keep charging.

Hi Conrad.

We had 30 hours darkness sharing last week - fortunately mostly in daylight.

All I needed was a little gas burner to warm up pre-prepared food and to satisfy my craving for coffee.

My other emergency power consist of a few rechargeable 2' lamps and a broken UPS.

We will all have a chance to comment on load sharing soon, and I beg you to grab the opportunity to suggest better ways. The invitation should be posted on www.gov.za under documents , documents for public comment.

I am not going to spend much money at this stage.

I will buy a second hand gas stove and water heater when the power supply is fixed. Our tariffs will rise sharply to fund the current expansions.

In SA we have plenty of fair weather hours per year. (we call it mooi (pretty) weather. it is a bit of a paradox because for a farmer it is pretty when it is overcasts).

With a solar water heater The geyser can be turned of for most of the year. These solar panels is a nice DIY project. Even a black rubber hose lying on the ground can provide enough water for a shower(s).

Ok the past few days we had what is known as "Geel perske reen" (yellow peach rain) and we haven't seen the sun for a few days.

my dear friend, why can't u go for SOLAR SYSTEM, IT IS EXPENSIVE BUT MAINTENACE FREE, & NO OTHER CHARGES U HAVE TO PAY FOR ITS USAGES, IT IS WORK WITH PHOTOVOLTIC CELLS, NO PROBLEM WHETHER U R USING 220 V 50 HZ, WE R ALSO USING SAME VALUE, INVERTER IS ALSO THE BEST .BUT HOW WILL U CHARGE THE BATTERY IF UR POWER GONE FOR 5-6 HRS A DAY...THINK ?

Solar panels can be extremely expensive. Payback is often calculated as 20 years. sometimes you need to take out a mortage to afford them.

Well, i have worked out that i will need about 350W from about 6pm untill about 9pm. Thereafter about 10W for 8hrs just to keep the one or two lights (energy saving lights) in the house on. The actual time might vary as the power is not always off the whole night. I can even go without the tv if needed. Then it will be about 40W untill 9pm and then 10W for the rest of the night. All the high wattage units will have to wait, fridges, stove, geyser, it will just get to expensive.

What i was thinking is this.....and help me if i am wrong......... I am going to buy 3 x 105A/h battery's and a 850W inverter with a 25A intelligent charger (trickle). I will have two housings if needed. I will install 2 x 0.1A 12V 150x150mm fans (one on each side of the one housing for the battery's) for venting. The inverter and charger in the other housing and mount the housings to my house external wall. I will then, from my distribution board in the house, run ac to the charger in the housing and then from the inverter run ac back in to the DB to a circuit breaker switch of lets say 5A. On this breaker i will only put the one plug in the bedroom (where my tv and sat decoder is) and the lights that i will need in case power goes off. All the other light and plug circuits remain as they are in the DB. Therefore, the plug in the room and the lights for emergency will always be working directly from the inverter. Power from distributer off or on. So if the power is cut they will just continue working, no switching or anything. What do you think?? Good idea??

My big question is this though.....

How does battery's hold up in climate change? They will be in a steel or plastic closed housing, standing on an inch of rubber. Can the charger and the inverter be in the same housing or should i make 2 housings? (In case of fire/explosion). I will put a isolator and circuit breaker in the housing too if need be. Temperature in SA ranges from about -5°C in winter to 36°C in summer.

Thank you for taking the time and advise

If your maximum load is 350W (correct me if iam wrong)or 350/.8PF=437VA your 850W invertor or 1062 va seems over sized please cross check the sizing of ups.

crm

You are correct. It is oversized but i am allowing room for future. It is easier to re-connect in the db than to sell inverter and buy a bigger one at a later stage. You never know what the future holds.

Well said.

It is a direction that I personally see no point in taking so log as they are SO expensive and SO inefficient!

Wind will provide more and cheaper electricity in many parts of the world for battery charging etc.......

Save your self some trouble and get a pass through inverter with charger (3 stage). what i did was wire the items i wanted to use through a seperate breaker box (1 breaker) and to inverter. When power goes off there is no interuption and upon return the batteries recharge.

An 800 watt should be reasonable price and size but a 1k should not be much more. you can start with 2 batteries and add 2 more when you relize what a life saver the inverter is. When you get a real hot night and can connect the fan you will be thankful for the spare capacity.

Thx. That is exactly what i want to do. If power goes out, it stays on and when it returns it just charges again. I am currently looking at 4 x 105 A/h and a 1200W inverter. The price is not all that different between 850W and 1200W. Like you said, rather have more juice than to little.

You may have already mentioned it, if so my apologies for bringing it up again, but make sure that your charger is intelligent and does not overcharge, but automatically goes onto trickle. If its adjustable, set it to say 13.6 volts, that way, although the battery will never get quite fully charged to 100%, it will also never gas......! A good point.

If you use Leisure batteries, you can run them well down without damage, though you should try not to do it too often as it will still shorten their life.

But car batteries will get a very short life if run below 12.6 volts very often.....that is the point at which a car battery will start to sulphate......leisure batteries of a size or two larger than you think you need are more expensive, but allow you more leeway with running low volts.....and will generally last many times longer than any car battery, assuming that you protect them for extremes of heat and cold etc etc..

A car battery is designed to allow high "Cranking Amps", a leisure battery of a similar physical size will not deliver such high "Cranking amps", but gives a far longer life span.....

"you pays your money and you makes your choice!"

Make sure that you read the manufacturers notes BEFORE buying a Battery!!

Hi Andy

Yes it is a trickle charger. What i need to know is this - Will the 25A charger be sufficient to charge 4 x 105A/h battery's or do i need maybe a 50A charger. Lets say that the power is only off for max 5 Hrs. The battery's are leisure battery's, but are deep cycles one's. So i think they will be fine. I already mailed the company for a quote. I just don't know if i can house everything in the same housing or if i need to put the charger/inverter in one housing and the battery's in another housing. Do i need to insulate the battery's in the housing against cold/heat?

Extremes of heat and cold are bad.

Having the charger in the same box can be beneficial, as long as you follow all safety codes and manufacturers instructions fully.....

Is the charger intelligent or dumb?, you never answered my point exactly....

thank you very much