Car Alternator as Human Powered Generator

N. Thornton · Jun 11, 2004

Zak <jute@zak.invalid> wrote in message news:<S0iyc.2562$9n5.1614@amstwist00>...

N. Thornton wrote:

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.

ah, I didnt know that.

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).

so are gears, and gears are needed for other motor types. Presumably
thats why I got the most out of a stepper. Thats the point I was
making.

Note there is more than one type of stepper, not all are good for the
job.

Also with steppers you run them at above their rated v, extracting
more v and the same i. This of course reduces the percentage effect of
the R.

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.

I was thinking there of a universal motor - forgot the 'mericans use
totally different ones in their washers. I agree an induction motor
would not be a first choice.

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?

yup, and was impressed. The only downside was it was all over in a day
- which fits this app perfectly.

Much better to
import zinc/manganese cells instead.

to the middle of nowhere in a 3rd world country? I'm doubtful, a
spoonful of salt costs a mere fraction the price. Steel electrodes
need replacing after a while, but scrap steel is about the most easily
found type of electrodes I can think of.

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.

Yeah, though I dont know for how long before the boiler needs refiling
- but even if it needed filling every 10 mins it'd be way less work to
run than pedal power!

Regards, NT

Captain · Jun 14, 2004

"gilbert" <gaubin@hotmail.com> wrote in message
news:c87ab623.0406101320.720f6973@posting.google.com...

Robin@HimalayanHandicraft.org (Robin) wrote in message
news:<af190b62.0405282214.1c145968@posting.google.com>...

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.

Kevin McMurtrie · Jun 14, 2004

In article <c87ab623.0406101320.720f6973@posting.google.com>,
gaubin@hotmail.com (gilbert) wrote:

Robin@HimalayanHandicraft.org (Robin) wrote in message
news:<af190b62.0405282214.1c145968@posting.google.com>...

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.

Yes, such an efficient battery. I run my entire home off vinegar cells.

Kevin McMurtrie · Jun 14, 2004

In article <af190b62.0405282214.1c145968@posting.google.com>,
Robin@HimalayanHandicraft.org (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

A check on Google finds some people who have experimented with this kind
of thing. Basically, you put a belt over the bare rim and drive the
alternator off that. Some designs allow the field coil power to be
reduced so the alternator is more efficient at light loads.

Some have also had success building windmills that will produce even
more power. This one is made of Volvos, wood, magnets, and wire:

http://www.otherpower.com/trips1.html

They even have a hamster wheel that runs a pair of LEDs

Jim Thompson · Jun 14, 2004

On Mon, 14 Jun 2004 00:26:27 -0700, Kevin McMurtrie
<mcmurtri@dslextreme.com> wrote:

In article <af190b62.0405282214.1c145968@posting.google.com>,
Robin@HimalayanHandicraft.org (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

A check on Google finds some people who have experimented with this kind
of thing. Basically, you put a belt over the bare rim and drive the
alternator off that. Some designs allow the field coil power to be
reduced so the alternator is more efficient at light loads.

Some have also had success building windmills that will produce even
more power. This one is made of Volvos, wood, magnets, and wire:

http://www.otherpower.com/trips1.html

They even have a hamster wheel that runs a pair of LEDs

480)460-2350 | |
| E-mail Address at Website Fax

Jamie · Jun 14, 2004

have them eat more beans!

)

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

Rich Grise · Jun 15, 2004

"Zak" <jute@zak.invalid> wrote in message
news:mZlyc.2578$9n5.2376@amstwist00...

Zak wrote:

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.

If you're going to buy stuff, how about, um, a generator?

Good Luck!
Rich

Rich Grise · Jun 15, 2004

"Zak" <jute@zak.invalid> wrote in message
news:HVhyc.2559$9n5.1563@amstwist00...

gilbert wrote:

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.

Well, yeah, that's what "battery acid" does. The reaction between the

acid (in this case vinegar) and the metal (in this case, iron) releases
electrons, or something like that.

I suppose you'd have to use fresh vinegar regularly, and as that other
person said, scrape the iron vinegaride off the plates. ;-)

Cheers!
Rich

Sage · Jun 16, 2004

I thought that the beauty of an alternator as opposed to a permanent
magnet generator, is that the field voltage is regulated, so it can
produce an appropriate voltage at any speed. A 120V DC 10,000 RPM
permanent magnet motor will produce 12V at 1000 RPM only - faster will
produce higher voltages and slower will produce lower. Since we need
to generate about 13.5 to 14.5 VDC to charge batteries, that puts the
cyclist to task for riding only at a very specific speed. But using an
alternator, a slower cylist will only produce lower current, but still
the ideal voltage.

If I am wrong about the theory of alternators, let me know.

Sage

"R. Steve Walz" <rstevew@armory.com> wrote in message news:<40B831FB.668A@armory.com>...

Roger Gt wrote:

X-No-Archive: yes
"Robin" <Robin@HimalayanHandicraft.org> wrote in message
news:af190b62.0405282214.1c145968@posting.google.com...
: 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?
-------------------
Nonsense, just turn down the field current, or use several people.

-Steve

Jim Thompson · Jun 16, 2004

On 16 Jun 2004 11:02:49 -0700, sagenepal@yahoo.com (Sage) wrote:

I thought that the beauty of an alternator as opposed to a permanent
magnet generator, is that the field voltage is regulated, so it can
produce an appropriate voltage at any speed. A 120V DC 10,000 RPM
permanent magnet motor will produce 12V at 1000 RPM only - faster will
produce higher voltages and slower will produce lower. Since we need
to generate about 13.5 to 14.5 VDC to charge batteries, that puts the
cyclist to task for riding only at a very specific speed. But using an
alternator, a slower cylist will only produce lower current, but still
the ideal voltage.

If I am wrong about the theory of alternators, let me know.

Sage

[snip]

You are correct, the field current and rotational speed determine the
output capability.

Other posters seem to imply that there's no control mechanism...
except for some types of motorcycle alternators, that shunt the output
with zeners, they are wrong.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice

480)460-2350 | |
| E-mail Address at Website Fax

Rich Grise · Jun 17, 2004

"Sage" <sagenepal@yahoo.com> wrote in message
news:e2c6ebeb.0406161002.3f537c8f@posting.google.com...

I thought that the beauty of an alternator as opposed to a permanent
magnet generator, is that the field voltage is regulated, so it can
produce an appropriate voltage at any speed. A 120V DC 10,000 RPM
permanent magnet motor will produce 12V at 1000 RPM only - faster will
produce higher voltages and slower will produce lower. Since we need
to generate about 13.5 to 14.5 VDC to charge batteries, that puts the
cyclist to task for riding only at a very specific speed. But using an
alternator, a slower cylist will only produce lower current, but still
the ideal voltage.

If I am wrong about the theory of alternators, let me know.

In the olden days, when cars had generators, they still had regulators,
which were just choppers. But the generators didn't put out enough at
idle to keep the battery even on float charge. I could see how today's
magnet technology could make a better generator, but it seems the
consensus is that a car alternator might be the cheapest, but it's
about the least efficient thing you could use.

Good Luck!
Rich

Sage · Jun 17, 2004

Here is the basic plan I am following:

http://myweb.cableone.net/adamsmed2/frntpg/page8/human.htm

This includes a rheostate which I will mount on the bike handlebars,
to allow the rider to regulate the voltage. That rheostat in turn
regulates a TIP-120 transistor, which in turn regulates *another*
TIP-120 transistor, which feeds the field coil of the alternator.

(I asked the above website's owner to email the designer of this
little system, but the designer refused to help because he thought
that Nepal was a Maoist country. Yes, there's a Maoist insurgency
there but I'm not working for them. In fact, they make this work much
more difficult because both the State and the insurgents are
suspicious that any equipment with capability will be used for their
enemy's benefit.)

Why are car alternators less efficient that permanent magnet
generators? By how much? Is this a trait of alternators versus
generators, or is it simply a matter of design because car alternators
are designed to run off of an abundant power source? Where could I
get a more efficient alternator? So much to learn.

I am also confused about the relationship of current to voltage in the
field coil -- an increase in voltage increases what? The voltage
output of the stator coils? An increase in field current increases
what? The physical resistance of the alternator and the stator output
current? These are my questions and my hunches. Now for more research.

In the meantime, the bicycle is all built and the alternator is
mounted. Now I am only waiting for the long belt to drive it. I
ordered a segmented belt from Woodworker's Supply, which may work very
well for this application.

Sage

"Rich Grise" <null@example.net> wrote in message news:<jZbAc.37080$tA6.30711@nwrddc03.gnilink.net>...

In the olden days, when cars had generators, they still had regulators,
which were just choppers. But the generators didn't put out enough at
idle to keep the battery even on float charge. I could see how today's
magnet technology could make a better generator, but it seems the
consensus is that a car alternator might be the cheapest, but it's
about the least efficient thing you could use.

Good Luck!
Rich

Zak · Jun 17, 2004

Sage wrote:

(I asked the above website's owner to email the designer of this
little system, but the designer refused to help because he thought
that Nepal was a Maoist country. Yes, there's a Maoist insurgency
there but I'm not working for them. In fact, they make this work much
more difficult because both the State and the insurgents are
suspicious that any equipment with capability will be used for their
enemy's benefit.)

Sad...

Why are car alternators less efficient that permanent magnet
generators? By how much? Is this a trait of alternators versus
generators, or is it simply a matter of design because car alternators
are designed to run off of an abundant power source? Where could I
get a more efficient alternator? So much to learn.

Well, cost is important, there is energy to spare, and the alternator is
designed to deliver around a thousand watts, not a hundred.

There is nothing wrong in principle with alternators, though the large
volume of iron to be remagnetized has higher hysteresis losses than if
the alternating field is in the internal iron.

I am also confused about the relationship of current to voltage in the
field coil -- an increase in voltage increases what? The voltage
output of the stator coils? An increase in field current increases
what? The physical resistance of the alternator and the stator output
current? These are my questions and my hunches. Now for more research.

A higher field current and voltage give a higher magnetic field. This
will mean a higher voltage for a certain speed.

If you want to be more efficient, use a chopper to drive the field coil:

+12 ---- T ---+---+
| | |
drive - 3
^ 3
| |
gnd ----------+---+

T is the power transistor: you will pulse it on. Note the freewheel
diode (this 'kees the current going' in the field coild then the
transistor is off. Without it, you blow the transistor and you do not
gain any efficiency.

In the meantime, the bicycle is all built and the alternator is
mounted. Now I am only waiting for the long belt to drive it. I
ordered a segmented belt from Woodworker's Supply, which may work very
well for this application.

Interesting to hear how things work out. Keep in mind that what you are
making is not a demo. While someone building an excercise cycle may be
happy with a demo cycle that delivers 15 watts out with 100 watts
excercise, you might want to aim higher.

I'm also curious how your belt drive works out - I assume it is a
V-belt. Toothed is better than plain, but a chain or a toothed flat belt
may be improvements. Or use a 'poly V belt' - here often used in washers
and dryers. Especially dryers use long belts.

I also just read a bit about using a series connected washing machine
motor (with windings on rotor and stator) - the poster claiming/guessing
that is 12 volt was connected to the stator, the rotor would be abouve
12 volts at speeds below 1000 RPM.

These are all from Euro style washers with horizontal axle and high spin
speeds.

Also have a look at
http://www.sciplus.com/category.cfm?category=174 (you are in the US?).
The first motor claims to run at 850 RPM at 12 volts while drawing 850
mA. This means the losses at that speed are about 10 watts. Your problem
when using this as a generator might be DC resistance though.

Thomas

Captain · Jun 17, 2004

"Sage" <sagenepal@yahoo.com> wrote in message
news:e2c6ebeb.0406170852.377e74cb@posting.google.com...

Here is the basic plan I am following:

http://myweb.cableone.net/adamsmed2/frntpg/page8/human.htm

This includes a rheostate which I will mount on the bike handlebars,
to allow the rider to regulate the voltage. That rheostat in turn
regulates a TIP-120 transistor, which in turn regulates *another*
TIP-120 transistor, which feeds the field coil of the alternator.

(I asked the above website's owner to email the designer of this
little system, but the designer refused to help because he thought
that Nepal was a Maoist country. Yes, there's a Maoist insurgency
there but I'm not working for them. In fact, they make this work much
more difficult because both the State and the insurgents are
suspicious that any equipment with capability will be used for their
enemy's benefit.)

Why are car alternators less efficient that permanent magnet
generators? By how much? Is this a trait of alternators versus
generators, or is it simply a matter of design because car alternators
are designed to run off of an abundant power source? Where could I
get a more efficient alternator? So much to learn.

I am also confused about the relationship of current to voltage in the
field coil -- an increase in voltage increases what? The voltage
output of the stator coils? An increase in field current increases
what? The physical resistance of the alternator and the stator output
current? These are my questions and my hunches. Now for more research.

In the meantime, the bicycle is all built and the alternator is
mounted. Now I am only waiting for the long belt to drive it. I
ordered a segmented belt from Woodworker's Supply, which may work very
well for this application.

Sage

"Rich Grise" <null@example.net> wrote in message
news:<jZbAc.37080$tA6.30711@nwrddc03.gnilink.net>...
In the olden days, when cars had generators, they still had regulators,
which were just choppers. But the generators didn't put out enough at
idle to keep the battery even on float charge. I could see how today's
magnet technology could make a better generator, but it seems the
consensus is that a car alternator might be the cheapest, but it's
about the least efficient thing you could use.

Good Luck!
Rich

Sage,

First of all, sorry about some peoples ideas about Nepal. I served with
several Ghurkas during my time in Oman and elsewhere, and I can assure
anyone willing to listen that the Neaplese are as intelligent as most
people, if not more so.

If you have water buffalo available, why not use them as a power source
instead of wearing out people pedalling a bicycle going nowhere. It will
take an extra step of "gearing up" but it might be an interesting and useful
next project.

With regard to the downspouts, by the time you've installed all the
waterwheels, pulleys, small generators etc, it strikes me that you'd have a
pretty haywire rig. All that water must run somewhere. Is it possible to
direct the flow from the downspouts to a holding pond and then use the water
in the pond to drive a single large wheel to turn your generator? How's
the local supply of bamboo? It makes pretty good pipes and there should be
people around you who have a lot of experience in using it to construct just
about anything.

Speaking as someone who bears scars inflicted by heavily armed, socialist,
peace lovers, I sympathise about the Maoists.

Regards

Cap

Rich Grise · Jun 18, 2004

"Sage" <sagenepal@yahoo.com> wrote in message
news:e2c6ebeb.0406170852.377e74cb@posting.google.com...

Here is the basic plan I am following:

http://myweb.cableone.net/adamsmed2/frntpg/page8/human.htm

Why are car alternators less efficient that permanent magnet
generators? By how much? Is this a trait of alternators versus
generators, or is it simply a matter of design because car alternators
are designed to run off of an abundant power source? Where could I
get a more efficient alternator? So much to learn.

I think it's because they have to run in dirt, and crud, and shock,
and heat, and vibration, and noise, and NOISE, and keep running for
years.

I was thinking it'd be interesting to see if you could rewind one;
I don't remember if it was here or some other thread or NG - but ISTR
somebody said even rewinding it, although it would help, still falls
way short of one designed for efficiency in a living room environment.
It has something to do with pole gap spacing or some such Magnetic
Black Magick Arcana.

I am also confused about the relationship of current to voltage in the
field coil

In the meantime, the bicycle is all built and the alternator is
mounted. Now I am only waiting for the long belt to drive it. I
ordered a segmented belt from Woodworker's Supply, which may work very
well for this application.

Borrow somebody's panty hose for the first smoke test. ;-)

Good Luck!
Rich

Steve · Jun 18, 2004

Rich Grise wrote:

"Sage" <sagenepal@yahoo.com> wrote in message
news:e2c6ebeb.0406170852.377e74cb@posting.google.com...
Here is the basic plan I am following:

http://myweb.cableone.net/adamsmed2/frntpg/page8/human.htm

Why are car alternators less efficient that permanent magnet
generators?

All alternators consume energy in their field windings creating the magnetic
lines of flux that must be cut (passed through) by the stator to generate
energy. For example, look at that schematic referenced on the web page
above. My numbers may be way off, but after you build & run the circut,
you can measure and tell us where the energy is going. Let's say 2 Amps
flow in the field winding of the alternator to create the required magnetic
field. So that's 2A x 12V = 24 watts. That's 24 watts NOT being delivered
to your batteries. (Purists - Yes I know that there's energy being lost in
the darlington pass transistor, but we're still looking at 2 Amps in a
series circuit feed by 12 volts.) If you're getting 100 watts to your
load, then your efficiency is 100 watts out/ 124 watts in = 80%. And
there's plenty of other losses that aren't factored in here (like IR
losses, eddy currents.)

By how much?
Is this a trait of alternators versus
generators, or is it simply a matter of design because car alternators
are designed to run off of an abundant power source? Where could I
get a more efficient alternator? So much to learn.

Good questions. My experience fails me. But you can't beat 0 field current
for a permanent magnets. Haven't I convinced you alternators are not the
most efficient way to go??? Cheap, available, yes. Efficient, not
usually. Google for do it your self permanent magnet generators.

I think it's because they have to run in dirt, and crud, and shock,
and heat, and vibration, and noise, and NOISE, and keep running for
years.

You left out the socially redeeming factor of cost. My guess is even a 100%
efficient alternator (Impossible, see above) would help gas mileage by a
minor amount, so manufacturers aren't even trying. In addition to the
factors you list above that are competing factors against efficiency,
weight & size probably rank high.

I was thinking it'd be interesting to see if you could rewind one;
I don't remember if it was here or some other thread or NG - but ISTR
somebody said even rewinding it, although it would help, still falls
way short of one designed for efficiency in a living room environment.
It has something to do with pole gap spacing or some such Magnetic
Black Magick Arcana.

I am also confused about the relationship of current to voltage in the
field coil

AOL
Me, Too!
/AOL

In the meantime, the bicycle is all built and the alternator is
mounted. Now I am only waiting for the long belt to drive it. I
ordered a segmented belt from Woodworker's Supply, which may work very
well for this application.

The bicycle powered alternator system I built was from an article in Ham
Radio magazine. (Not _a_ Ham Radio magazine, that was _the_ name.) It
suggested, and I used with great success, a couple of bicycle chains to
loop around the alternator and the rim of the bike tire. Attached to the
shaft of the alternator was a 5 speed gear cluster. The chain drive meant
you didn't have any pulley belt slippage, at least at the alternator.
Surprisingly, black electrical tape wrapped about the rim held up for many
hours of operation. Now you may have to use leather or rubber to last
longer, but there's so much contact area on the rim that there's really no
slippage to speak of to rip up your "rim pad."

Borrow somebody's panty hose for the first smoke test. ;-)

Good Luck!
Rich

OK, now for the "flames." ;^) Unless I missed what the Original Poster
eventually said, there's 3 - 75 Amp-hour 12 Volt batteries in this system.
Let's see --- that's 75 Amp-hour * 12 V = 900 watt-hours. Times 3
batteries = 2700 watt-hours. If you can produce 100 watts of power from
your bike power system, that's 2700 watt-hours / 100 watts = 27 hours of
pedalling. Oh, don't forget, there's charging inefficiencies. So it's
probably more like 35 hours to fully charge dead batteries. Fortunately,
your batteries will & should never be dead, but we're still talking serious
hours pedalling. Man, 3 - 75 Amp-hour batteries. I know I'd be dead after
pedalling to charge 'em, even to 25%! IIRC, with my bike generator [sic -
bike alternator] system I could power a 100 watt load for say 15 minutes.
50 watts, over an hour. 175 watts, expect to pass out in about 2 minutes.
It was a steep power curve. I never did an efficiency estimate or
measurement on my bike system, so YMMV. Good luck, I honestly think you
may need it.

Seriously, please do some power budget calculations. See www.homepower.com.
How much KWH per day do those radios take? Can that power be replaced by
humans each day? Not enough data given to tell.

Thanks, Steve

Car Alternator as Human Powered Generator

N. Thornton

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