Generator question

[mike n]

Hello. I have a 63 40hp evinrude and I just finished putting new bearings in the generator.the brushes are in great shape.how can I reverse the polarity. It reads -.03 volts when spinning clockwise with a drill.

mn

[frankr]

It needs to be polarized. To bench test and polarize at the same time:
1. Use a jumper wire to ground the field terminal (the small one) to the case.
2. Use another wire to ground the case to a 12V battery negative post.
3. Use a third wire to connect the armature terminal (the larger one) to 12V battery positive post.

With the above hookup, the generator should run slowly like a motor. This also polarizes the generator.

[mike n]

Thank you. If it runs slowly like a motor does that mean it should charge ok or should I bench test it some other way. I know the drill doesn’t turn it that fast

mn

[frankr]

That proves the generator is ok. But as you said, the drill isn’t even close to turning it fast enough. It will put out a small voltage at drill speed, but in order to produce enough voltage to close the relay and charge the battery, the outboard needs to be turning 1500-2000 RPM. That’s crankshaft speed. Because of pulley sizes, the generator is turning much faster.

[mike n]

thanks for the great info

mn

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