Friction driven alternator experiment?

Speedy Wilson · #1 03-16-2009, 10:39 PM

I was looking around the forum, just reading and such, then out of left field it hit me. I hear all these guys talk about the range they get or lack of on an electric powered bike. My idea is to mount a GM style Delco one wire alternator onto a bike and drive it with a friction setup. Use the Juice generated to charge the battery or batteries while in motion. They are hardly any parasitic drag to turn. It has an internal regulator and come in 12 and 24 volts.Most are light and would be easy to mount up. If a car engine can idle at say 800 rpms and the ratio is about 2:1 between crank pulley and alt. pulley it would spin at 1600 rpms. Most will make about 50 to 60 amps i would think at this speed depending on output rating of the alternator. The key is to find a way for it to spin up this high from riding on the tire in a friction setup. Could use a friction drive mounted to a gearbox to spin it up faster at a slower wheel speed? I'm not that great at the math of calculating the ratios but If I had the parts I would try it just to see if it would work. If anyone has tried this or have any thoughts let me know. All great inventions started with an idea right?

toytime · #2 03-16-2009, 11:03 PM

I'm just not sure if the power used to drive it will be equal to what it gives you back in return.

cityevader · #3 03-16-2009, 11:05 PM

perpetual motion machine?!?!

toytime · #4 03-16-2009, 11:11 PM

That's about it-nothing comes for free.
The thing is that if it even gave you an extra hour of use, that can double your mileage and with ebikes that is large.

Speedy Wilson · #5 03-16-2009, 11:36 PM

True,it would be some drag but i can spin an alternator pulley fairly easy by hand. With some type of low friction bearings in the drive setup,use aluminum mounts it may add about 8 to 10 pounds. Or i was thinking about those really old (indian or harley) bikes that had a big pulley mounted on the rim,at a say 20 to 1 ratio that thing would really spin up.

cityevader · #6 03-17-2009, 12:15 AM

You can easily spin an unpowered alternator by hand. With the field energized, considerable torque is required to spin it. A car's computer will increase the idle air valve to maintain steady rpm when electrical loads increase.

Doesn't make sense to run an electric motor to spin a generator.

deacon · #7 03-17-2009, 12:16 AM

Here is the only problem I would have my bike is 24volts the alternator is 14max. I doubt that it would do much good.

It takes several hours to charge the batteries from the bike so I'm not sure the alternator would do much even if it was 24volts. But if you have one, I would give it a try.

On a car the battery is only used for a few seconds then the alternator charges it as long as you drive the car. Still Give it a try I would if I had one laying around.

Speedy Wilson · #8 03-17-2009, 12:36 AM

The 24 volt alts. usally come off small diesel engines or backhoes. I had a 12 volt alt and a couple car batteries here somewhere,but i need a 12v motor for my tests. I was going to bench test the idea by the running time of the motor on a battery alone versus the running time with alt. backup. Spin the alt. at about 1500rpm with a washing machine motor to simulate being driven by the wheel.But then that is constant and riding is varied speed. Im starting a gas weedeater/mt.bike build so i don't want to go in an opposite direction on my only bike, though I am going to give this idea a shot once I get the funding for parts and another bike. I will keep you posted on what happens...be it works or bombs.

deacon · #9 03-17-2009, 12:44 AM

Quote:

Originally Posted by Speedy Wilson

The 24 volt alts. usally come off small diesel engines or backhoes. I had a 12 volt alt and a couple car batteries here somewhere,but i need a 12v motor for my tests. I was going to bench test the idea by the running time of the motor on a battery alone versus the running time with alt. backup. Spin the alt. at about 1500rpm with a washing machine motor to simulate being driven by the wheel.But then that is constant and riding is varied speed. Im starting a gas weedeater/mt.bike build so i don't want to go in an opposite direction on my only bike, though I am going to give this idea a shot once I get the funding for parts and another bike. I will keep you posted on what happens...be it works or bombs.

Good luck and let us know sounds like an interesting experiment. They say you can run a car's starter motor on the bike as a friction drive and that is 12 volts.

Speedy Wilson · #10 03-17-2009, 12:51 AM

hum..i may have an old chevy starter...wont it burn out? I'm thinking that because when cranking an engine its on for what,5 seconds max? Will consider that too. Thanx for idea,will keep you posted on it.