Car Alternator as Human Powered Generator

[Rich Grise]

Many thanks to all for the input, let me respond to a few of the
suggestions:

- Solar/Wind Power: Is great, we have a wind generator but every
summer there is a period of about three months of solid rain/fog when
there is no wind or sun.

When it starts raining, swivel the windmills upward.

Cheers!
Rich

 

[Don Bruder]

Water wheels on the rain gutters. The higher your funnel, the more work
you can get out of it.


I'd think for this you'd need a substantial capital investment
in cesspits and collection systems and stuff. _I_ wouldn't put
money into it!

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.

 

[BlackWater]

The GM alternator has a mildly magnetized rotor.

Very good.

An alternator is a CURRENT SOURCE.

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.

A little knowledge is a dangerous thing ;-)

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'.

 

[Jim Thompson]

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

 

[Sage]

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.

 

[Sage]

True about the not being portable but micro hydro will work on runoff.
(works here. in winter)

Still, a major installation compared to a bicycle. and definitely not "on
demand"

Fritz

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

-Sage

 

[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

 

[Ed Price]

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

-Sage

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

Ed

 

[Robin]

There has been much noise and warm air about micro generation techniques.
Little useful will come from this speculation before the OP states what kind
of load and duty cycle he needs. Once he defines his needs, then he might
also disclose his assets; available money & labor & time, geography, local
fuel assets and local weather. Even local social customs may be a huge
factor; for instance, possibly one of those Sherpa guys, who can climb to
20k feet without breathing heavy, might be able to put out prodgious power
from a bicycle generator at 8k feet. OTOH, he may be prevented from doing
this by viewing this as a less than honorable task for a Sherpa man.

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

 

[Ed Price]

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

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 (<g>), but maybe Viet Nam,
Thailand or Australia.

Ed

 

[Rich Grise]

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 (<g>), but maybe Viet Nam,
Thailand or Australia.

Ed

 

[Rich Grise]

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

 

[gilbert]

I do some volunteer work that provides rural villagers in Nepal with
WiFi communication (See http://NepalWireless.net if you are
interested). As part of this work, we need to develop a human powered
generator to charge our solar batteries when there is no sun for
months on end. Is a car alternator and a bicycle a possibility? How
much current/voltage does a typical alternator produce and what RPM is
necessary? These are both readily available in Nepal, so they would
be idea. Thanks very much.

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.

 

[Rich Grise]

[email protected] (Robin) wrote in message


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

 

[Don Bruder]

Please explain to _me_ how to do it.

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...

 

[Rich Grise]

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...

Thanks!
Rich

 

[N. Thornton]

Many thanks to all for the input, let me respond to a few of the
suggestions:

- Solar/Wind Power: Is great, we have a wind generator but every
summer there is a period of about three months of solid rain/fog when
there is no wind or sun.

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.

- Methane/dung: This would be great not only for electricity but
cooking, light, etc. I have heard it is not possible to do this at
altitudes over 3000m, but if you know a way please tell me.

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

I think I am going to look into something a bit smaller than a
generator. If anyone knows a good motor or generator available on
line could you send me a link.

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

 

[Zak]

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.

Doesn't work. A battery primarily consumes metals.


Thomas

 

[Zak]

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.

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.

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.

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).

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.

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.

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.

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

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.

That is a nice idea - these run on anything.


Thomas

 

[Zak]

That is a nice idea - these run on anything.

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