Generating electric from a car engine

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I ran across an article in an old Mother Earth News about generating electricity from a car engine mounted on a stand with a large alternator(unfortunately it wasn't very detailed). This fellow also generated a lot of hot water when he ran the car to charge up his battery bank. Well after this spell of cold weather we have found that the house we bought is very drafty and hard to keep warm, so we will begin building a cordwood home in the spring. I'd like to wire it strictly for DC(to avoid the cost of an inverter and we don't use many appliances anyhow). I plan to have a water storage area that would facilitate a gravity water supply to the house. This would mean that I would only need to run my water pump once or twice a week..at the same time I could be charging my battery bank. Can anyone give me any suggestions of how to do the wiring? I've read books about wiring DC but they have been confusing even though I have done conventional wiring before. I also need any advice or ideas about how feasable the engine idea is..any tips or suggestions on type of alternator or type of engine too. Thanks!

-- Amanda in Mo (aseley@townsqr.com), December 20, 2000

Answers

Amanda, this looks like a pretty good idea in theory, but it's a bad idea in real life. Sounds a bit like most of the things those hippies were telling us. Oops, sorry about that. Anyway, this would be a cheap way to set up a system, assuming you have an old car to donate to the cause. In the long run, it's a disaster.

Is this a plan you are committed to for many years? Even the smallest automobile engine will use many times more fuel than one suited to the task you describe. It will also wear out faster, need more maintenance, and spew more pollutants than a smaller engine.

Look for a 12 volt generator with at least a 100 amp alternator powered by a small, high-quality, overhead valve engine or a small diesel. There are advantages and disadvantages to both. Either will last you ten to fifteen years of semi-weekly usage with proper care. Either will quickly pay for itself in reduced fuel and maintenance costs when compared to a salvaged automobile engine.

You can also buy smaller, cheaper generators that will not last as long or produce as much power efficiently. It's a matter of how long you want to use this system and how much money you have to spend up front.

Look at the generators on these sites: www.gennydeecee.com www.wildernessenergy.com

Also, someone on this forum talked a while back about designing and building 12 volt generators. I think it was Hoot. How 'bout it, Hoot?

-- Jim (catchthesun@yahoo.com), December 20, 2000.


Amanda! Jim is right---on ALL counts! Your best bet [assuming you want it invest very small amounts of cash] is to secure a one cylinder Briggs engine and hook it to an automobile alternator. You was talkin about 12vdc anyhow--what better way to generate it than with common parts that's easily and cheaply obtained! An alternator from a late moded GM product are ususally in the nieghborhood of 75 amps. A good 5 or 6 hp engine will turn it without much trouble. In wiring the house-run at least 10awg,[rated at 30 amps] single conductor-stranded wire with either T, or THW insulation. Parallel circuits for lights, appliances etc. Keep lights and appliances off same circuit while fusing at no larger than 30 amp fuses. You can not use a "split phase feeder" on D.C. You'll have to run a neutral [ground wire] to each light or appliance. We are still worry'n about our production models of the cheapie gensets. Prices are too high for equipment for it to be feasable for resale or production--unless we can buy the eq. cheaper. We haven't given up on this and will keep tryin to secure the parts at a reasonable cost. Good luck. hoot. Matt. 24:44

-- hoot (hoot@pcinetwork.com), December 20, 2000.

This would work sort of although as already pointed out would burn lot of fuel. If you really need the hot water, I'd look for smallest water cooled diesel I could find. I have seen small water cooled Kubota, Yanmar, etc surplus diesel engines listed in Burdens Surplus catalog out of Lincoln, Nebraska. Still cost couple grand for one, but would last long time.

Now if I remember, the old TMEN also did a series on running a car engine off wood gases. This might just be economical with an old car engine. If I remember, you needed maybe larger engine since wood gas has much lower energy content. Remember them using a large 6 cylinder to run a sawmill, and think they rebuild an early 1960's Pontiac Tempest 4 cylinder (200cubic inch)engine for a generator(this is a large 4 cyl). They also made a pickup run on same principle driving it across country and believe they used a big block V8 for that.

-- Hermit John (hermit@hilltop_homestead.zzn.com), December 20, 2000.


I'm sorry I didn't make myself clear. I was planning on using a 4 cylinder engine to run a larger alternator...lol....not running a large engine. The idea of using a small motor instead of an engine is an interesting idea. Hoot you lost me on the wiring (was greek to me), could I say walk into my local hardware store and ask for that type of wire? Don't most household wires come with a ground wire incorporated? Thanks

-- Amanda in Mo (aseley@townsqr.com), December 20, 2000.

Amanda! I doubt if a regular hardware store would know but one could try. The best source is an electrical supply store. I'll email ya direct with more info. Thanks. hoot. Matt.24:44

-- hoot (hoot@pcinetwork.com), December 20, 2000.


Amanda, let me see if I can help some with the wiring. The regular AC wire you are talking about is THREE stranded. AC is quite a bit different from DC. In AC one of the three wires is for ground, the other two for the power and will be something like lamp cord, 16 gauge, or three conductor Romex. With DC you only need TWO wires, one is positive and the other the ground, or negative. (I know there are exceptions, but this is simple and straightforward.) Generally DC wire carries more amps so the wires need to be a little bigger. 10 gauge should be more than enough to handle most applications in the household.

-- JLS in NW AZ (stalkingbull007@AOL.com), December 21, 2000.

I remember a story in MEN years ago where a guy used a 4 cylinder motor from a Vega or some throw away car. It had a generator attached to it and once a week he ran the engine to pump water from a deep well, in to an overhead storage tank, (which garvity fed back to his house)the hot water from the cooling system was used to take showers and it seems there was some other by-product in the scheme. I suppose if you had the engine laying around and the gen-set it would make sense, If you had a tractor W/PTO you could do the same thing but not get the shower, still, I thought, for the time, it was a pretty good idea except that where I lived, a storage tank would surely freeze in the winter and a plain ole, 5KW generator would serve the same purpose, except for the shower. If you can gravity feed your water system then you can run it through a water heater, wood fired or otherwise. If you get to manby gadgets going half the time, half of them are not working.

-- Hendo (redgate@echoweb.net), December 21, 2000.

I'm glad this came up -- my husband told me a few days ago that he was buying an old VW engine to use as a generator -- I have always felt that it would be a bad idea, so it was good to see some hard facts! I've e-mailed this thread to him at work -- hope he sees it before he leaves for the day!!

-- Kathleen Sanderson (stonycft@worldpath.net), December 21, 2000.

I think I'm the one that gave Amanda the idea--I've been looking for the right engine for some time.

A car engine turning a couple 100 amps worth of alternators (you need more than one to do it in a cost effective way) will charge a battery bank in a hurry using less fuel than a smaller, less efficient, engine. A 5 or 8 HP mower engine will have to run at near capacity the whole time it's running. This greatly reduces it's lifetime. A car engine will be running at an idle, or slightly faster. There is far less wear on a large engine running at a few percent of capacity than a small engine running full tilt.

The other thing is she needs heat. A water-cooled diesel will produce as many BTUs of heat per gallon of fuel as an oil furnace will. You won't be able to catch all of the heat, but a well designed system will catch most of it. This means you can say you are paying for heat and getting the electricity for free in the winter. An air-cooled mower engine loses all of it's heat. Of corse a gas engine will be about the same BTU/dollar as diesel, but the comparison to heating oil isn't as direct.

Also with a bigger engine, you can use the same engine for doing different jobs; like pumping water or turning a heat-pump's compressor, if you want to do the tinkering. If done right, it can be cost effective compared to grid-power.

I tried pointing Amanda to a few web sites that I thought talked about wiring. I still don't have time to see if the information is still there. You need to calculate your average and peak loads for each circuit to figure out what wire is optimal. ‘Rules of thumb' may work in most cases, but usually by making you buy heavy wire even for where it may not be needed.

==>paul

-- paul (p@ledgewood-consulting.com), December 21, 2000.


Just another .02 worth.

If you go the route with the water cooled engine, you might consider that fact in your home design. Create a large amount of central mass (sort of like the Russian stove idea) and circulate the fluid through it to 'store' the heat. You'll also need to consider the summer weather also. So I'd guess you'll also need a diversion for the hot water. Shouldn't be too hard to put the piping and valve arrangements together.

I don't know if this would be an issue but the water pump on your engine would be moving a bunch of water (in terms of quantity and distance). I don't think they are designed to work under much static pressure. You might need to use some additional pumps (electrical?) to help circulate the water.

I assume you're going to use some sort of heat-exchanger design. I don't think I'd want the cooling fluid from my engine flowing throughout my residence. Besides, it might be useful to have all that water in a semi-potable state if you should need it.

Anyway, just a few things that came to mind.

j

-- j (jw_hsv@yahoo.com), December 21, 2000.



Paul, you got me remembering and thinking. A couple of years ago I was in Iowa and had a chance to go through an old flour mill built in the 1880's using an overshoot waterwheel. Off the main milling room was a small shop and the shop was powered by a single shaft that was gear driven off the waterwheel. It also had a clutch arrangement.

This main shaft powered several small machines used in the repair of the mill. Most of the machines were missing, but you could see how they worked. A pulley and belt from the main shaft powered each machine. When you wanted to use a machine, you opened the clutch, belted up the desired machine and re-engaged the clutch.

A remote shop is sorta like that today. In place of the main shaft is a central generator with a large motor and the belts driving the machines are electric wires. The machine pulley is its own individual motor.

The more things change, the more they stay the same.

-- JLS in NW AZ (stalkingbull007@AOL.com), December 21, 2000.


It morning (early) and I am still thinkin' about this. Sounds like a good winter project, don't need the electric, but interesting. Don't know much about modern car engines (70 and later). The question I am wondering about, will a small four cylinders newer (say 85 to 90) engine work WITHOUT the car's computer? Is any model better than others?

-- JLS in NW AZ (stalkingbull007@AOL.com), December 22, 2000.

JLS,

I used to do volunteer work at a couple old gristmill museums. One even used the shaft from a grain auger that ran between the mill and a storage building to transmit power to run its grain elevators and such. That mill ran 5 pairs of stones a couple sifters, grain cleaners and all of the elevators and such from two 22' wheels. Too bad there wasn't much of the inner workings left anymore.

About the car engine. The truck I'm driving now is the newest model-year vehicle I've ever owned. It's a ‘78. I know past some point, there isn't any recognizable gear-driven distributer and the computer cannot be tossed out. I'm hoping to find a VW diesel, like out of a pickup or a Rabbit. I don't know if they can run without a computer or not, but I'd like the option of making biodiesel for fuel. Any other small diesel that comes my way at the right price will work, but as far as I know the VW ones are the most common small diesels and are easy to get parts for. I wouldn't turn down a Mercedes, but I'm less likely to find one in my price range.

==>paul

-- paul (p@ledgewood-consulting.com), December 22, 2000.


Thanks Paul, I am still ponderin this question. Expect one could all so power a heavy duty compressor with a BIG tank for a lots of air tools. I'll wait until after Xmas and then maybe do a post of appropriate engines from cars. Amanda, I did not mean to hog your thread - just kinda happened. If you have questions on wiring, I will be more than happy to try to answer. Just email me.

-- JLS in NW AZ (stalkingbull007@AOL.com), December 22, 2000.

No problem JLS :o). Paul is a friend of mine. Ya'll trade ideas to your hearts delight. I'm getting ideas from it....hubby says this is a bad thing(when I get ideas) but I think it is great!

-- Amanda in Mo (aseley@townsqr.com), December 22, 2000.


I find this to be a very interesting subject! The idea of using a junked car engine is very attractive, after all you will find a perfectly good engine that is dumped only because the body work is rusted, smashed or just out of fashion. I would not expect to find a good utility engine in the same condition for what would be practically free.

Just a few suggestions off the top of my (greying) head:

The typical car engine would drive a number of 100 amp alternators! I think I would look for an alternator that could handle a significant portion of the engine's potential output.

Try to get hold of the whole car, not just the engine and use as much of the wiring etc as you can, essential if it is a later model electronic engine.

Try to recover all the heat you can. Make a heat exchanger for both the coolant liquid and the exhaust system.

There are dozens on sites on the net describing miracle systems for extending gas mileage in your road car. Many ideas are plain wacky but some have potential for a stationery, constant load condition like your generator system. Do some study of old tractors like the Massey Harris Pacemaker (circa 1936?). Those old engines would burn low grade fuel, kerosene, parafin, turpentine etc, because they had heated carburettors, simple water injection and widely variable spark timing. Fuels not intended for road use will likely have much lower taxes (well, in this country anyway!) and what might be almost impossible to set up for a road vehicle may be practical for a stationery, constant load situation.

If you don't mind some serious spanner work it might be practical to convert a couple of cylinders to be air compressors. It might not be very efficient but losses in the way of friction will go into heating the coolant and I expect largely recovered by the heat exchangers.

Cheers.

-- john (john@cnd.co.nz), December 23, 2000.


Hi John, I thought about your idea to use a cylinder or two for a compressor a coupe of days ago and then decided to go with a free standing compressor with maybe an electric clutch. The problem I see in converting cylinders is that you have to modify the fuel injection or carburetor to NOT deliver gas to those cylinders. Then there is a potential timing (computer) problem. My initial thought was this is starting to get a little too complicated, so I shelved this idea for the time being. I have read somewhere an alternator under full load of charging will use 5 to 10 horsepower. Someone else may have better numbers. In any event the idea of three or so alternators for rapid charging appeals to me. Lets see now we have three alternators, a compressor, a water pump (for gravity fed water system). Guess the water pump will need a clutch also. Does anyone know where to buy electric clutches (belt style)?

-- JLS in NW AZ (stalkingbull007@AOL.com), December 23, 2000.

There are Amish farms that use a small gas engine and a wide slack belt to drive their piston waterpumps when the windmill won't pump enough. You could easily drive a slack belt from a modified rim of a jacked-up car. Keep the transmision and clutch and you can select the speed for the job at hand. The mills I mentioned before used slack belts and pullies a lot. They are fairly simple to rig up, including using an idler wheel as a clutch. Simple move the idler until the belt goes too slack to turn the wheels.

There are a number of commercial industrial air compressors that use a V8 block. 4 pistons firing driving four to compress the air. There used to be a kit for doing the same idea with an old VW engine, but in general it's not a backyard tinkerer's job.

Go to http://redhouse.com/rda/housers/ and click on the co-generation section. This is a group of people that build huts for homeless people. They power a cluster of huts from an old car and capture the heat for hot water.

Homepower magazine has plans in their download section for a replacement for a car's voltage regulator that makes it a constent current source, instead of a constant voltage source. Supposedly this works better to recharging dead batteries. http://www.homepower.com/

==>paul

-- paul (p@ledgewood-consulting.com), December 23, 2000.


Amanda, hoot, I'd do most anything to avoid using battery storage of energy. But that's another subject.

Hoot, as far as using 10 gauge wire, I'd think amanda would do well to determine just how much juice she will be using on whatever circuits she's using. Remember that 12 volt power will be operating with ten times the amps (meaning ten times the wire size) in comparison to 120 volts, with the same amount of watts.

Amanda, you will need a lot bigger than ten gauge wire to carry the juice from a 75 amp generator to wherever it is going (I assume to a battery bank?) I don't have a wire chart in front of me, but I think you'll need something in the order of number four copper, or maybe even number two. I know that number six is normally the size used for fifty amp circuits, so seventy five amps should need a size or two larger.

Also, for what it's worth, the "neutral" is not the same as the ground, although a lot of folks confuse the two.

As far as heating your water, this is a very high energy use, and one I don't recommend doing with alternately generated electricity. I would strongly recommend heating the water with either propane (a time tested method) or wood. I have heated water with firewood for over twenty years, in the winter, and solar in the summer (also a very simple and cheap source of hot water in summertime--I can tell you how to make a very simple solar water heater for less than fifty bucks, or a very sophisticated one for less than a hundred, not including the tank)

I made my own wood heater, and incorporated a water jacket which heated both the house and the hot water. It was not nearly as efficient at heating the house, unfortunately, since the water jacket tended to reduce the combustion temperatures.

If I were doing it again, I'd have a separate wood powered water heater. There are several sources of these already on the market. They are made in Mexico, and are designed to burn pine cones and such, I think. The only source I can remember for sure is Real Goods. They tend to be very expensive; maybe find the brand name on their website, then look for this name on a web search.

Good luck!

JOJ

-- jumpoffjoe (jumpoff@echoweb.net), January 07, 2001.


here are my .02 car engine if your a machinc and a machemist and have the money for fuel go right a head otherwise look at the resource you may have stream,wind stream build dam small waterwheel to drive a altenator 50 amp 600w conneted to a storage battery the bigger the better wind put up a tower same. get a standy genset for occasional use. size (watts) slightly larger than your largest power device eg. circular saw waterpump lights wireing standard 14g is okay from distrution box but no daisy chain home runs on all circuts anything else check power requirments for wire size on a small system like this to much power drain will kill your battery hot water: wood stove put a (jacket L shape) outside the stove unless you want steam suggest copper pipe 2inch dim.L shape bolted to stove near top with tail (short part) down (cold in)from watertank bottom long end hot to a hotwater tank top reason for jacket outside stove safer will take longer to heat water

-- nick (raymondetdesrosier@smpatico.ca), January 25, 2001.

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