Does anyone know how to put together a bicycle powered generator for charging car batteries (12 volt DC)?

-- Duane Schnabel (schnabel@smgazette.com), January 26, 2001

Answers

start with an old working bike,, get an old working alternator,, replace the back wheel/sprocket with the alternator. Run the wires to the battery, peddle away. Going to have to make a stand for the bike also,, keeping balance while stationary on a bike is TOUGH. Id use a GM alt. they have a built in regulator,, just in case you peddle to fast,, but I wouldnt think thats a problem. I built a little generator on a lawnmower base with an alternator,, worked fine,, and was pretty mobile to get over rough ground.

-- Stan (sopal@net-port.com), January 26, 2001.

Duane! Stan is correct! You'll need a switch connected from the positive [hot]side of the batter to terminal "L" on the alternator. I used a GM from a 92 Pontiac hooked to a 5 hp briggs engine. Fast idle about 800 rpm is sufficient. In addition to the built in regulator those newer ones are a lot easier to turn than older units. The Pontiac is rated at 75 amp. Countryside Magazine published an article I sent to'm on how to build a cheapo genset using this same GM alternator. I think it was the Nov-Dec issue of 1999. hoot. Matt.24:44

-- hoot (hoot@pcinetwork.com), January 26, 2001.

Hi Duanne I for one would not start with an automotive alternator. I doubt automotive alternators are the most efficient convertors of mechanical energy into electric power. Someone mentioned 800rpm, that sounds like crankshaft speed and my Ford (1999) appears to have about 2 to 3 step up so we are looking at 2000 rpm at the alternator. To do that with a bike will require a big step up in the chain ratio, maybe two stages. Just turning that would be tiring enough without the load of the alternator.

I suggest you look for a high efficiency DC motor such as were in old mainframe computer tape drives. You wont have to turn them very fast to get a useful output but you will need a regulator circuit although I dont know what would be wrong with a simple blocking diode. Certainly if I was on the pedals I would never over-charge the batteries!

Unfortunately I think it will take you several hours to charge even a small car battery.

-- john hill (john@cnd.co.nz), January 27, 2001.

the army uses a hand cranked generator,, and its an alternator from a DODGE,, Inknow it doesnt crank very fast, but it also has gears.It gets used to jump trucks,, run 2 way radios,, so maybe a 10 speed would work

-- Stan (sopal@net-port.com), January 28, 2001.

Stan is right an alternator will work fine the speed will be ok.The rear wheel sans tire makes a mighty big pulley.The problem with the set up is humans can only produce about 1/6 of a hosepower for any length of time.the lawn mower trick is a much easier option.Look around the web site www.epicenter.com.there are pplans for both the bike and the lawn mower engine version.(e-mail me if you can't find it as I have it on cd-rom) good luck duane let us know how the project works out.

-- Greg (gsmith@tricountyi.net), January 29, 2001.

I look forward to reading a report from anyone who connects up an alternator in the ways suggested.

-- john hill (john@cnd.co.nz), January 29, 2001.

as I stated earlier,, I used the lawnmower one,, still use it at the hunting cabin every year,, it'll run a skill saw,, TV and VCR with some lights, drills. Not the biggest generator, but certainly the cheapest, and works for small needs,, and chargeing batteries is what alternators are designed for.

-- Stan (sopal@net-port.com), January 29, 2001.

Seems like I got Johns hackles up a bit.Since I don't want to continue to injure his kiwi pride.I must say that John is right.An ALTERNATOR would be a real mother to try and peddel with a bike.A GENERATOR would work and I have used an automotive generator to charge a battery.It has it's limitations.Humans=1/6 hp.I think part of the problem John is americans tend use the term generator/alternator interchangably as applies to automotives.They both produce electricity but are not the same in function.I do wonder if an alternator might be used in a stationary bike given a large pulley (tire removed) and a switch to the (field coil?) to prvent needing to start the bike at full load. I have also built the lawnmower engine/alternator gen set and it works like a champ.Thank you for being so subtle John.

-- Greg (gsmith@tricountyi.net), January 29, 2001.

Thanks for all the responses. The lawnmower generator sounds like a good idea, but I wanted go get away from a gas powered engine because of hauling & storing gas here. What I have to work with is an old exercise bike and a 1955 GMC 12 volt generator. The idle speed on the GMC is 500 rpm. I thought by running a serpentine belt around the tire on the bike and the pulley on the generator I might peddle up to that rpm and charge the battery.

-- Duane (schnabel@smgazette.com), January 29, 2001.

was thinking about this,, how about useing a functional bike,, have a mounting frame, where the back wheel would run against the small pully of the alt.,,would have to be a wide pulley, to accomadate the tire,, but with that kind of gearing, large tire, to small pulley,, should get ALOT of rpm

-- Stan (sopal@net-port.com), January 29, 2001.

OK thanks Greg, I must try not to get too prickly! :-) I did a few figures and estimate that to spin the alternator/generator at about 800 to 1000 rpm only requires a pedalling speed equal to 4 or 5 mph, depending on the small pulley of course. I think there would be less friction with a drum shaped pulley of say 4 to 6 inch diameter. May I suggest an experiment with the bicycle mounted in a frame and the pulley of the chosen generator (or whatever) bearing against the tyre, no wires connected. Do some pedalling runs to gauge the effort required. I think this will demonstrate the mechanical wastage of the setup. There may be scope for some experimentation at this stage, playing with the size of the driven pulley for example as it may be possible to arrive at an optimum ratio. The increase in effort required once the wires are connected will (I think) be fairly much what will be available as electrical output. One horsepower is equal to about 60 amps at the voltages we are interested, so taking the available hp (at the legs) as 1/6 we are left with something less than 10 amps. If you know the amp/hour rating of the battery you can easily workout the time you can expect to spend charging it up. This subject is becoming so interesting I might even try it myself!

-- john hill (john@cnd.co.nz), January 30, 2001.

The current issue of "Home power" magazine (at homepower.com) has an article about a pedal-powered generator. I have seen some at the Midwest Renewable Energy Fair at Amherst, WI, over the past 11 or so years, and some of them used generators from 12 volt aircooled VW beetles, and worked well.

Jim

-- Jim (jiminwis@yahoo.com), January 30, 2001.

Good point Jim, I agree the generator from a 'Vee Dubyah' would be more suitable than an alternator.

-- john hill (john@cnd.co.nz), January 30, 2001.

Rob Roy made a pedal-powered generator for his cordwood-masonry house. It is described in his book, which is advertised in many back-to-the-land/country magazines. I think of using this type of device when my kids are running around the house, stir-crazy in the winter. Good luck.

-- Bob Blessum (robertblessum@netscape.net), February 02, 2001.

Hi Duane. A fellow in St Paul is selling his bicycle powered battery charger, though as I understand it, this one has a couple extra bells and whistles. It is a 10-speed with a stand for holding the rear wheel off the ground when using like an exercise bike to charge your battery bank. The extras are: This bike has a battery of its own - you can take it off the stand and it becomes an self-propelled electric bike!

I do not know what price he is asking, but I do know how to reach him. (sorry, you'll have to cut and paste, I do not know how to make a hotlink): john@stpaulmercantile.com

Also, there has been some talk about marketing a kit to turn your own bike into one of these smartbikes. Any interest in that?

Sandy

-- Sandy in MN (jpevans_56353@yahoo.com), May 08, 2001.

Hello there... this thread got me thinking. I'm wondering how much wasted energy is produced by an automobile gen/alt... i.e. once the car battery is charged. Would it make sense to put two or more batteries in the car and let the spares charge while driving?

cheers and best, Max

-- Max (Maxel@inwindsor.com), May 09, 2001.

As I understand it Max, once the battery is charged the output of the alternator/generator drops (contolled by the voltage regulator) so that it is powering all those electrical things that we all like, heater fan, radio, wipers, lights, etc etc. A second battery is a reasonable idea if you want power for lights etc (e.g. camping) without the risk of not be able to restart the vehicle. What would be a good idea might be an alternator powered by all the heat that is wasted in the exhaust.

-- john hill (john@cnd.co.nz), May 09, 2001.

the bicycle powered generator reminds me of a friend who wanted to cure his couch potatoe tv-watchng kid. he hooked the generator up to a bicycle and to only an old motorcycle battery. The battery wouldn't hold a charge so the kid had to pretty much keep peddeling to watch tv. The battery just acted as a voltage regulator somehow. After about a month the kid stopped watching tv.

-- Robert Bodell (webmaster@marine.mail22.com), June 01, 2001.

Here is the answer to everyone's question:

1. Do not use an alternator.

2. The supplies you need if you want to charge a battery:

a. 12-36 volt permanent magnet dc motor b. 300-600 watt dc/ac inverter. c. reverse diode to keep the battery from reversing polarity and turning the pedals on the bike. d. flywheel to control spikes in charging. e. bicycle chain works better than a belt.

Watts = Volts x Amps

Use this calculation when buying the motor. There are a lot of motors that only produce 0.5 Amps.

I have successfully built a bike that powers a T.V. and VCR.

-- Dennis Taber (dltabor@kscable.com), July 30, 2001.

Can anyone on this forum tell me what all items are required to Power 5 100 watt bulbs (Lights) for 8 hrs?

Thanks in advance.

Rathin ( rathinvaidya@yahoo.com)

-- Rathin Vaidya (rathinvaidya@yahoo.com), September 05, 2001.

how do you wild a generator from scratch

-- tom (phsychokid212@cs.com), January 25, 2002.

Sir,

The easiest thing to do is go to the junk yard, buy a heater blower motor from a Mazda Navajo and hook the input wires to a full bridge rectifier, available from radio shack. You will not need a regulator because the field consists of permanent magnets. I do not know at what rpm it will have to turn. It's efficiency should be as good or better than an automotive alternator because you will not have to energize a field. I have been thinking about the very same thing for a wind charger.

-- Norm Czerski (zyphir@gci.net), February 23, 2002.