# Car Alternator as Human Powered Generator

Discussion in 'Electronic Basics' started by Robin, May 29, 2004.

1. ### RobinGuest

Hello All,

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.

Robin Shields

2. ### Roger GtGuest

X-No-Archive: yes
: Hello All,
:
: 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.
:
: Robin Shields

The Short answer is NO! Takes about one horse power and about
2000 RPM... Not something most men can do for any length of time.

Wind mill maybe?

4. ### Rich GriseGuest

Do the experiment! Take a bike, and take the tire off the back
wheel, and use it as a pulley. Run a belt around it and the generator
/alternator pulley, and use an ordinary 12V battery/regulator. Then
pump away! A man can easily generate 1 HP for awhile, and if you're
in really good shape, you can pedal an airplane across the English
Channel.

In fact, I seem to remember doing an experiment in HS physics class,
where they went to a 2-flight stairwell and had a couple of volunteer
boys run up it as fast as they could. They timed it, and calculated
the kinetic energy expended, and some guys made almost .75 hp. So I
think any old ordinary person on a bike could make enough electricity
to run a radio or something. In fact, in the Science Musem in St. Paul,
MN, they used to (maybe still do) have setups exactly like that, with
a TV right in front of you and I think meters.

As to RPM, I really don't think it matters that much, as long
as it's more than some threshold value. I can visualize a belt
around a bike wheel driving a "standard" alternator, and I can
almost hear it whirring. It just intuitively, to me, seems to
"automatically" run at the right speed. And you can get 10- and
more- speed bikes!

Good Luck!
Rich

5. ### BillGuest

How about animals and gears?

Bill

6. ### Fritz OppligerGuest

been there, done that. it will be a long uphill stretch of road to pedal
though. For a rikshaw jock no problem.
They run entire sound stages at alternative energy shows from banks of
bicycles. Ganging up is definitely a plus.
Put a rheostat on the field so you can adjust.
put it in the hotel lobby so the fat tourists can work out some.

7. ### Henry KolesnikGuest

Oxen or other animals going in a circle with a drive to the alternator.

8. ### CWattersGuest

This site may be of interest...
http://ww2.green-trust.org:8383/2000/humanpower.htm

Some info on using a car alternator here.
http://www.lookout2000.com/windpower/

The main problem is that you need 800 to 1000 rpm at least to drive a car
alternator (Note gearing up in photo of the windmill on the page above). A
human works best at <100rpm so you would need 10:1 gear up at least. Gearing
up isn't very efficient.

This web site (scroll down it)..

http://homepages.enterprise.net/hugh0piggott/books/

...has plans showing how to make an alternator out of a brake drum and links
to other interesting stuff.

Colin

9. ### SoerenGuest

Hi Robin,

I think you would be better off with generators with permanent magnets and
of a smaller size (or even DC-motors in reverse?), like some slightly
owergrown bicycle dynamos.

--
Regards,
Soeren

* If it puzzles you dear... Reverse engineer *
New forum: <URL:http://www.ElektronikTeknolog.dk/cgi-bin/SPEED/>

10. ### Jim ThompsonGuest

Absolutely! I worked on the electronics for an exercise bicycle that
used an alternator as a variable physical load AND provided the power
for the circuits.

...Jim Thompson

11. ### BobGuest

Very interesting. It looks like the answer to Robin's question is yes.

Bob

12. ### Robert C MonsenGuest

Hasn't Lee Felsenstein (of Homebrew Computer Club fame) already done
this for a village in Laos? Perhaps you can contact him, or any number
of folks who worked on this

http://www.usatoday.com/tech/news/2003-02-12-net-pedaling_x.htm

Alternately, you could contact Jon Katz, who has set up homebrew hydro
power generation in the Domican Republic using a three phase motor, a
controller, and some space heaters:

http://www.cnn.com/SPECIALS/2000/virtualvillages/story/dom.rep/interviews/

I suspect you can contact Jon at his Cornell email address for more
information.

Anyway, good luck with your project.

Regards,
Bob Monsen

13. ### Roger GtGuest

X-No-Archive: yes
"Bill" wrote
: "Roger Gt" wrote
: > "Robin" wrote

: > : Hello All,
: > :
: > : 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.
: > : Robin Shields
: >
: > The Short answer is NO! Takes about one horse power and about
: > 2000 RPM... Not something most men can do for any length of
time.
: >
: > Wind mill maybe?
: >
: How about animals and gears? Bill

Messy, But an Ox on a "go around" pulling an arm could be geared
up to do it. Someone would need to clean up after the ox though!
That would require an attendant to care for the ox.
The typical alternator from a small car or pickup will produce up
to about 50 amperes at full rpm, but it also draws power from the
battery for the field current. So disconnect it when not in use!

The gear ratio is really big. Lets see, an Ox walking around once
ever 15 seconds, to get 2000 rpm. Gear up is 8000/1. It's doable
but messy.

1. First you need a 6 foot diameter pulley mounted on the center
of the "go-Around" ( Nominal 4RPM) a belt drives a 2 inch pulley
gets you a 36/1 ratio to provide (144RPM), then the 2 inch pulley
shaft drives a 30 inch pulley, this belt drives a 2 inch pulley on
the alternator at 2150RPM. Gee, only two stages!

I'll leave the simple mechanics up to your available materials....
and ingenuity!

If the oz moves slower you need more gear up! A 36 inch secondary
pulley will allow the Ox to go around in 20 seconds! (3RPM)

Gee, why do villagers need Wifi? Can't they just talk to each
other? My fathers farm doesn't have Wifi. No one misses it! The
Cows least of all! They just kick a soccer ball around the
pasture for entertainment!

14. ### Mark (UK)Guest

Hi!

Could you not just put the Ox in a field to graze, stick a pipe up it's
rear, collect the methane, then use that to drive an engine, or burn it
to generate steam to power a turbine to run the alternator!

I'm not too sure of the Cubic meters per hour one average size Ox
produces tho.....

Yours, Mark.

15. ### Roger GtGuest

X-No-Archive: yes
A prime example of true British Thinking!
Cubic meters? How about cubic "cubits?"
I'll let you insert the tube!
(Top posted in response to a TOP POSTER!)

"Mark (UK)" wrote
: Hi!
: Could you not just put the Ox in a field to graze, stick a pipe
up it's
: rear, collect the methane, then use that to drive an engine, or
burn it
: to generate steam to power a turbine to run the alternator!
:
: I'm not too sure of the Cubic meters per hour one average size
Ox
: produces tho.....
:
: Yours, Mark.

<snip>
: > : How about animals and gears? Bill
: >
: > Messy, But an Ox on a "go around" pulling an arm could be
geared
: > up to do it. Someone would need to clean up after the ox
though!
: > That would require an attendant to care for the ox.
: > The typical alternator from a small car or pickup will produce
up
: > to about 50 amperes at full rpm, but it also draws power from
the
: > battery for the field current. So disconnect it when not in
use!
: >
: > The gear ratio is really big. Lets see, an Ox walking around
once
: > ever 15 seconds, to get 2000 rpm. Gear up is 8000/1. It's
doable
: > but messy.
: >
: > 1. First you need a 6 foot diameter pulley mounted on the
center
: > of the "go-Around" ( Nominal 4RPM) a belt drives a 2 inch
pulley
: > gets you a 36/1 ratio to provide (144RPM), then the 2 inch
pulley
: > shaft drives a 30 inch pulley, this belt drives a 2 inch
pulley on
: > the alternator at 2150RPM. Gee, only two stages!
: >
: > I'll leave the simple mechanics up to your available
materials....
: > and ingenuity!
: >
: > If the oz moves slower you need more gear up! A 36 inch
secondary
: > pulley will allow the Ox to go around in 20 seconds! (3RPM)
: >
: > Gee, why do villagers need Wifi? Can't they just talk to each
: > other? My fathers farm doesn't have Wifi. No one misses it!
The
: > Cows least of all! They just kick a soccer ball around the
: > pasture for entertainment!
: >
: >
: >
: >
:

16. ### Rich.AndrewsGuest

(Robin) wrote in
It takes a fair amount of power to run an alternator at full output. If
you take a 50 amp alternator, ground the output and fully energize the
rotor coil, ir will stall out a large 6 cylinder Cummins diesel engine.
As a matter of fact it will stall it out so quickly, that a bystander
would say that you shut the engine off.

r

17. ### mikeGuest

Don't they have wind in that part of the world?
If you must pedal, I'd think about a lower RPM generator so you don't
use up all the energy overcoming mechanical losses.
mike

--
Return address is VALID.
Bunch of stuff For Sale and Wanted at the link below.
Toshiba & Compaq LiIon Batteries, Test Equipment
Yaesu FTV901R Transverter, 30pS pulser
Tektronix Concept Books, spot welding head...
http://www.geocities.com/SiliconValley/Monitor/4710/

18. ### JeffMGuest

Absolutely! I worked on the electronics for an exercise bicycle that
Now mention that it requires a battery in good shape
(or a live electrical outlet) to boot it.
An old '50s style PM automotive generator
doesn't need an electrical source for its field.

19. ### Jim ThompsonGuest

Where in the world did you get that idea? Must be some weenie engine!

12V at 50A is only 600W, even presuming something like 50% efficiency
that's only 1.6hp.

IIRC a typical automotive 50A alternator takes about 6hp input at
(alternator) 14,000RPM.

...Jim Thompson

20. ### Jim ThompsonGuest

A GM alternator doesn't either, to get it started, then it requires a
minimum load, or it goes over-voltage. GM calls that load "daylight
headlights" ;-)

...Jim Thompson

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