Car Alternator as Human Powered Generator

To burn dung as fuel requires only the labor to collect the dried cow-chips/road apples and deliver 'em to the fire. Things get messier (but can still be easily started (and later expanded, if the situation warrants) using a couple of nested barrels and some water) if you want to do a methane generator.

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Very good.

Mr. Ohm says something about current times resistance equals voltage ... the battery has resistance, ergo the 'current source' will supply 'i'-amount of current at 'e'-voltage to the battery with resistance 'r'. The voltage would be infinite if the circuit was open, but there are, fortunately, limiting factors.

So, you're saying that GMC now includes superconductive batteries in their pick-up trucks ? If it's less than a superconductor but more than a perfect insulator it's a 'load'.

[snip]

You implied using a battery to limit the output voltage of the alternator. That's patently insane. An unregulated alternator will blow a battery away... I've had it happen. My test stands at Motorola (in the mid-1960's) ran 50 alternators at a time.

[A point of amusement... all GM alternators had bearing failure at almost exactly the equivalent of 55,000 miles... just out of warranty :]

...Jim Thompson

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|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
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|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
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I love to cook with wine.      Sometimes I even put it in the food.

Yes, they have wind, but not so much during the monsoon, when there is also little sun in the daytime. We have a wind turbine but it's sitting still most of the time.

Also, there is not enough water runoff on top of peaks, which is where radio repeaters are best located.

-Sage

Yes, there's wind, but not at the right times. There is no wind in the monsoon, which also happens to be the time when there is not enough sun many days to power the batteries. There is in fact a wind turbine at this location but it sits still almost all the time.

- Sage

"on

And the monsoon is thick enough to blanket even the peaks?

Ed

Hi Ed, Sorry, I just saw your request today. We would probably use this generator to charge up two 75 amp-hour batteries, either going through a Trace C35 charge controller or using a voltage regulator for the alternator. Money and time are scant, which might not be surprising. I would like to do it for $100, (I have a bike already), but $150 seems a lot more reasonable. We have people working on the project who are very, very strong and would be willing to pedal.

Best Robin

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Well, then just a few comments. With even a crummy, cheap bicycle generator, I think you can get about an amp or so at 12 VDC. If you use the typical setup of the generator shaft having a roughened drive disc which is pressed against the tire, then you will likely have seriously degraded tire life. The large "gear ratio" of the cycle wheel to the generator drive disc puts a lot of stress on the tire at the contact point, scrubbing rubber away at a surprisingly fast rate.

OTOH, maybe you can use a more exotic DC motor as a generator (some posts have recommended motors with very strong magnetics), so your efficiency will improve. I would also try to drive the generator directly from the chain, to eliminate tire wear and efficiency loss. I wonder if you might be able to find an old WWII human-powered generator (used in life-boats and for clandestine services; I recall one model being referred to as a "Gibson Girl" ). Foot-pedaling one of these might be a way to avoid using the bicycle at all.

Don't know of any Nepalese surplus stores (), but maybe Viet Nam, Thailand or Australia.

Ed

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Sorry, accidentally hit "send," right after I decided not to send it.

Why complicate things with mechanical stuff containing moving parts that will break down eventually? Make them a set of batteries with different metals so that they only have to pour in vinegar once in a while. I suppose they can make vinegar, can't they? If not, explain them how to do it.

Please explain to _me_ how to do it.

Thanks, Rich

Vinegar in a nutshell: Make a batch of wine, using whatever the local "favorite fermentable" and standard method happens to be applicable. Don't water-lock it (or balloon-cap it, or any of the other usual methods of sealing the carboys for fermentation)

You'll have at least weak vinegar in short order...

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Don Bruder - dakidd@sonic.net - New Email policy in effect as of Feb. 21, 2004.
I respond to Email as quick as humanly possible. If you Email me and get no 
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Thanks! :-) Rich

A car alternator has 3 main problems. Low efficiency, very high run speed, resulting in a lot of friction losses and gearing losses, and energy used to run the field coils. Yes it works, but you could do much much better.

I found a stepper motor very good: runs at very low rpm to produce enough v and i. Less work than a geared 2000rpm motor: gears arent entirely efficient.

Washing machine motors can be upcurrented by ading a transformer to reduce V and up i: get the motor upto speed before switching on the connection to the transformer. If you leave it connected it'll be much harder going to get speed up.

But I'd vote for salt cells myself, if salt is available. These use steel and carbon as electrodes, and produce about 0.5v per cell. Pour in salt water when power is needed, and they run for about a day. Empty and scrub the steel clean, and off they go again. I'm sure all that egnerating labour could do something else, it has value.

Persumably one could also use vinegar, though more work. Ferment anything that can be fermented, then expose to air and the alcohol turns to acetic acid.

Burning shit is easy enough, lots of power in it.

Have you looked at a Mamod stationery engine? These toy steam engines can have a motor/generator added to produce power. Run them off shit, dry plant matter, anything you can burn. Multifuel ability is a real bonus when youre in the middle of nowhere.

Although we understandably frown on playing with shit, when resources are real tight its a real power source. It doesnt smell when burnt, and once completely dry the bacteria etc die off. It is long burning too. In fact there was a power station built some place in England, that ran on shit. (Probably Dung-eness or something)

Regards, NT

Doesn't work. A battery primarily consumes metals.

Thomas

Also high eddy current losses (try turning one when the coil is energized) and high losses as it is designed to be current limiting at higher speeds.

But stepper motors are inefficient - the coil resistance is usually high compared to theinductance at running speeds (which is what you want for a stepper, but not for efficiency).

Depends on the moto. Asynchronous ones are hard to use as a generator: the inductance connected to a capacitor, and the generator spun at the renonance frequency. Then when voltage builds up, apply the load, and take cre of voltage regulation. Works very well for delivering bower back to the grid.

Ever run such a cell and looked at the power it produces? Much better to import zinc/manganese cells instead.

That is a nice idea - these run on anything.

Thomas

As for the generator: go with a high quality permanent magnet DC motor. If money is a problem, try the reel motors of old 19 inch tape drives or something similar. If money is not a problem, talk to a motor manufacturer - you might still get a good price and/or help with this interesting application.

If I were selling these, I'd get a high discount out and some extra help. And with luck you might find a sponsor.

Thomas