Canex Inc.____________________________

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Drive Motor Faults in Electric Vehicles

Be sure to check grounds first






Vehicle does not travel at all.


- Check battery voltage at the battery

- Check voltage at the drive motor with the drive wheels blocked securely off of the floor and at full throttle. If voltage is not present, check cabling and control.

​- If voltage is present at the motor and the motor does not run, check for open motor.






Vehicle runs but low torque, poor acceleration, grade-ability is poor, but final top speed with no load may be higher than normal. ( operating time per battery charge may be low )


- Check for field weakening option and check for stuck field weakening contactor or improperly operating field weakening.

- Check control current limit setting.

- If field weakening is functioning properly, the motor may be defective.

( Motor current may be higher than normal. Check motor current and compare reading to that of normal vehicle with wheels off the ground at full throttle. Opens or shorts inside the motor alters performance and usually causes higher than normal motor current.)






Vehicle travels slower than normal and/or poor grade-ability.


​- Check for proper operation of 1-A and/or field weakening.

- Check for bind in the drive train.

- Check for proper tire size and compound.

- Check for motor voltage with wheels securely blocked off floor in 1-A. The motor needs full voltage to run at full speed. ( voltage  should be within about 0.7 volts of battery voltage )

- Check control current limit.

-Check for proper brush grades. ( Especially on 12 volt systems )

- The motor may be defective.

( Motor current may be higher than normal. Check motor current and compare reading to that of normal vehicle with wheels off the ground at full throttle. Opens or shorts inside the motor alters performance and usually causes higher than normal motor current.)





Motor overheats and/or fails.


- Review the application to see how the equipment is being used. An application with a high number of start-ups, extremely long runs under full load, or pushing/shoving loads may be an application issue that needs to be addressed.

- Check for binding in the drive train that will cause higher than normal currents.

- Improper battery cycling and/or improper battery charging maintenance procedures.

- Totally enclosed motors are de-rated. More than a moderate duty cycle may cause overheating. If this is suspect, review the situation with your management.





Motor has arcing under brushes.


- Check for proper brush grade.

- Check for brushes hung up in the brush box.

- Spring tension to weak.

- Confirm that motor cabling matches schematic.

- If motor has compound windings or inter-pole windings, the connection for these windings may be reversed.





Motor has short brush life.


- Review the application to see how the equipment is being used. An application with a high number of start-ups, extremely long runs under full load, or pushing/shoving loads may be an application issue that needs to be addressed.

- Check for binding in the drive train that will cause higher than normal currents.

- Application may contain contaminates, such as abrasive dust or chemicals.

- Check for improper brush grade.







 




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