charging batteries

[guruji]

Dear Sir I have a 24v dynamo and trying to charge a 12v battery.The thing is that when connect it to battery the dynamo starts to rotate cause it's with brushes.Do I need a cutout or other device to charge the battery and cuts from it at same time?

[ghurd]

You need a diode between the dynamo and battery.  This will stop power from the battery making the dynamo from running like a motor.  The diode shouyld be between the dynamo + positive, and battery + positive, with the stripe on the diode toward the battery + positive.

The minimum diode should be at least 50V PIV, and at least 6A.  The diode may need to be bigger depending on the dynamo and expected amp output.  I like at least double the expected amp rating for a diode.

G-

[ghurd]

Looking at your other post.  Possibly you would do better with a home made alternator or an AC induction motor conversion.

G-