This forum is in read-only mode. Please continue to browse, but replies are disabled for now. Why?

Short in the motor?

I had the same "we moved and the scooter doesn't go anymore" issue. I think there's a short in the motor. Connecting batteries directly to motor results in voltage dropping from 25v to 0v, and a separate ohm/continuity check on the motor wires (bypassing the controller) shows 0 ohms. Is there any recourse other than ordering a new motor? Doesn't seem like I can open the motor to find the short... if the short is in the spring-protected wire I don't see a way to expose that either. Thanks for any advice! -Gary
I should specify this is a Razor crazy cart :)
For a good battery pack to drop from 25 Volt to 0 Volts an extremely large load, such as a short circuit, would need to be placed on the battery pack which would immediately burn out the fuse in the battery pack's wiring harness.

If the battery pack Voltage is dropping to zero and its fuse is not burning out then the battery pack is old, worn out, or faulty.

The resistance of brushed DC motors can be difficult to measure so if a 0 Ohm reading is measured from the motor that could be a false reading. A good secondary test to perform on the motor would be to connect a multimeter set to 20 DC Volts to the motor wires and spin the wheel that the motor is attached to while reading the Voltage on the multimeter. If the motor generates any amount of Voltage at all then it does not have a short circuit. Another good secondary test to perform on the motor would be to wire it to a 12 Volt automotive battery charger (not an automotive trickle charger or the Crazy Cart's battery charger though!) and see if the motor spins when powered by the battery charger. If the motor spins when powered by the 12 Volt battery charger then it is good and does not have a short circuit.

Please let us know how it goes.

Connecting a DC voltmeter and pushing the cart does generate a few volts (2-3 volts).  I don't have a want to connect a charger to the motor and check it out - but based on this you feel it might be the battery pack?  The charger claims fully charged when I plug it in to charge the batts, it turns green and batteries measure 25V.

thanks for the help 

If the motor generated electricity then it could not have a short circuit and there is no need to test run it on a 12 Volt automotive battery charger.

Your diagnosis results point towards the battery pack being faulty. If the battery pack Voltage dropped from 25 Volts to 0 Volts and its fuse did not burn out that is proof positive that the battery pack is bad.

The 25 Volts fully charged Voltage level is another indicator of a problem with the battery pack. The Razor Crazy Cart's 24 Volt battery pack should recharge to around 27.6 Volts.

A bad battery pack will usually recharge normally and the charger will show fully charged, however, when a load is placed on the battery pack then its Voltage will significantly drop to the point where it will not operate the motor.

Login or Signup to post a comment