Ezgo Marathon has me puzzled.

[JohnnieB]

Originally Posted by orangeman6

Just curious and always trying to learn, how did that make the cart faster?

I have no idea of what was done to the cart LukeL was working on, but shorting or partially shorting the stator windings in a series motor will up the RPM it turns for the voltage applied. Since the motor loses its low end torque, the shorting has to be done while the cart is moving at or near its top speed with the field circuit intact.

The difference between a torque motor and a speed motor is the relative strength of the magnetic fields generated by the armature and stator windings. A relatively strong stator magnet generates more low end torque and less top speed while a relatively weak stator magnet generates less low end torque and higher top speed. Shorting or partially shorting the stator windings reduces the strength of the stator magnet. The strength of the stator magnet does not go to zero when shorted due to the induced currents from the rotating magnetic fields generated by the spinning armature.

I'm speculating, but shunting some or all the amps around the stator windings of DC motors using switches and relays probably evolved into feeding the stator and armature from different power sources and varying the relative magnetic strengths of the stator and armature electrically, creating what is now known as a SepEX (Separately Excited) motor.

[LukeL]

Originally Posted by JohnnieB

I have no idea of what was done to the cart LukeL was working on, but shorting or partially shorting the stator windings in a series motor will up the RPM it turns for the voltage applied. Since the motor loses its low end torque, the shorting has to be done while the cart is moving at or near its top speed with the field circuit intact.



The difference between a torque motor and a speed motor is the relative strength of the magnetic fields generated by the armature and stator windings. A relatively strong stator magnet generates more low end torque and less top speed while a relatively weak stator magnet generates less low end torque and higher top speed. Shorting or partially shorting the stator windings reduces the strength of the stator magnet. The strength of the stator magnet does not go to zero when shorted due to the induced currents from the rotating magnetic fields generated by the spinning armature.



I'm speculating, but shunting some or all the amps around the stator windings of DC motors using switches and relays probably evolved into feeding the stator and armature from different power sources and varying the relative magnetic strengths of the stator and armature electrically, creating what is now known as a SepEX (Separately Excited) motor.

This is exactly what had been done, but, with a very thin gauge wire. The wire had melted to the case of the motor causing a dead short. I completely removed the whole modification. It had been set up so when the pedal reached the bottom, it triggered a micro switch to activate a solenoid to bridge the motor terminals (with thin wire!)


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[JohnnieB]

Originally Posted by LukeL

This is exactly what had been done, but, with a very thin gauge wire. The wire had melted to the case of the motor causing a dead short. I completely removed the whole modification. It had been set up so when the pedal reached the bottom, it triggered a micro switch to activate a solenoid to bridge the motor terminals (with thin wire!)


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Should have used at least same gauge cable as the cables feeding the motor.

Sounds like they need a refresher course on Ohm's Laws.

[LukeL]

Yep. It was a bad job anyway and the owner was glad I got rid of unnecessary modifications. Now we know why it quit in a small hill.


Club Car DS driver’s club #59