Friction driven alternator experiment?

deacon · #11 (**permalink**) 03-17-2009, 07:34 AM

some say they will burn, some say they won't.. I would use it in pulses not for extended time. Like run it on the hills but turn it off going down hill. Kick it on to get the speed up on the flats then let the bike coast some before you bring it back on again. that kind of thing. When i was young stupid and poor I used a household switch for my starter button on an old toyota. So you can use one of those as your on off switch.

Now that part fascinates me. How the starter will work. Those should be very easy to find in almost any town.

cityevader · #12 (**permalink**) 03-17-2009, 09:05 AM

I too would be interested to know your experiment results. But to get the most simple results, use a 12 volt drive motor instead of a 120 volt one.
With a proper amp meter, get a baseline measurement of drive motor current draw, then see what additional draw draw is required while the alternator is charging (not merely spinning), then compare it to the amp reading coming out of the alternator. This will show any viability.

Do friction drives not allow regenerative braking? Wouldn't that be easiest without additional componentry?

deacon · #13 (**permalink**) 03-17-2009, 10:48 AM

okay my understanding. I'm not at all sure that I'm right, is that all brush type motors convert to generators when spinning faster than they are drawing current. However you need a diode to pervent the current from running back to the motor. The controller on some motors do that have the diode built in. So when the throttle is turned off or low the motor is free wheeling and becomes a generator. I have run my friction drives both ways and have never seen any significant difference. On the hub brushless motor absolutely a difference.

Auto alternators have the diode pack built in which allows power to travel only one direction. If you ran a starter motor for push and an alternator for charge you will probably get the same effect only a little more so since the alternator will be charging even while the starter motor is pushing. that's my guess

Speedy Wilson · #14 (**permalink**) 03-17-2009, 07:56 PM

Somebody tossed my alternator! Probably went in trash pile when my Pa cleaned up behind the barn. First rule of being a gearhead is never throw away parts even if you think they are useless. I went to wally world today and seen a "hybrid" e bike for 399.00. I will give 50 for a back wheel and the drive motor...lol..the setup looked sweet...very compact. Anyway,I have to find an alternator and starter or twelve volt motor...I wonder about electric wheelchair parts. I think I know where one was...got to check on it. The next challenge i see is adapting a drive wheel to the starter motor. Could dremel out the nose cone and fit a sprocket somehow. Will be a few weeks on this one...the bill collectors cometh...untill then ride on guys...

deacon · #15 (**permalink**) 03-17-2009, 10:23 PM

I really am curious to see what a starter motor does. I think I would like to try one as a friction drive.

ottolynx · #16 (**permalink**) 04-05-2009, 09:36 PM

I also interested in finding out if this work, I current working on my senior project for school and our group idea is to take a electric moped and attach a alternator to it to charge the battery but where lost on ideas that why I interested in knowing the resultof your experiment.

Cabinfever1977 · #17 (**permalink**) 04-05-2009, 09:50 PM

2 stroke gas bike engine,small lightweight and powerful.
hook it to a 12 or 24 volt alternator.
use the alternator to charge deep cell batteries to power electric motor.
then you can say: officer im running off of the electric motor,the gas engine is a generator to charge the batteries.

cityevader · #18 (**permalink**) 04-05-2009, 10:55 PM

I'm kicking myself for not taking a picture...I just sold my gym-type elliptical excercise machine and tried to lighten it by removing panels, etc. Surprised to find the sole component for resistence was that the pedals/handlebars spun an alternator, an exact car alternator wired to two large resistors to dissipate heat. That thing would put out so much resistance that the Hulk would have a hard time spinning it. I apologize for being such a negative nellie here, but the only way to get any reasonable charging on an E-bike is coasting downhill. From what i've read about electric bikes, it doesn't take much headwind to slow them way down and reduce range. High resistance from "charging" would do the same.

toytime · #19 (**permalink**) 04-06-2009, 01:07 PM

That is interesting "city". Where did this power go to?
You are so correct about wind slowing you down on an ebike.
There is no such thing as free power and if anything, cabinfeaver has the right idea but a small generator can be had for under $200.
I've always followed these threads but they always die off with nothing ever being accomplished

cityevader · #20 (**permalink**) 04-06-2009, 01:54 PM

The power went into gigantic resistors and dissipated as heat.