Electric Bike Generator Issues

[jjmoen]

Hello!

I have a 1/8 hp motor that we were hoping to use as a generator. It is supposed to turn at 810 rpm when supplied with 230 V and 2.7 A. When we spun it at 810 rpm, we only got 4 V though. Are we doing something wrong or is the motor defective? Or does the motor not respond the same when going from mechanical to electrical as it does in reverse?

Also, the shaft can move about 1/2" into and out of the motor. Is this a problem?

Thanks!

 

[spad4me]

WATTS UP DOC!!!

One hp equals around 750 watts

Your motor is 1/8 hp.
1/8 of 750 is around 93 watts.
Now Volts X Amps also equal Watts.
230 X 2.7 = 627 watts.
93 watts in.
627 watts out .
You just solved the energy crisis .
NOT!!!

You also forgot friction losses, wire losses, hysteresis losses, and a few losses that I may have forgot. Like ac or dc plus the powerfactor of the motor .

 

[jjmoen]

Good point. The motor has written on it all the values I've given though. Hmm...

We considered friction losses, etc., but if it really puts out 230 V, friction losses wouldn't reduce it to 4 V?

Also, it is an AC motor. As on motor: HP 1/8, RPM 810, HZ 60, PH 1, V 230, A 2.7. Did we understand something incorrectly?

 

[liveforphysics]

If it's an AC induction motor, it can't start generating power until you provide a correctly phased current into the motor to create a field in the rotor.

Generally only AC induction generators (not AC motors) will have exciter windings and slip rings needed to create this field and start the device operating as a generator.


You want a motor with permanent magnets for being a generator.