400 Amp Solenoid Diode and Resistor


Just ordered a new 400 amp solenoid but forgot to order a Suppression Diode and Pre-charge Resistor are these essential for the cart to function. I’m not exactly sure what they do?


Some solenoids have them built in so it depends on which solenoid you bought. The golf cart will run without them but it's not advised.


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They will not stop the cart from running but they're there to protect the controller and to charge it use the old ones


"A pre-charge resistor is a device that slowly charges the capacitors inside a electronic speed controller before it is powered up. Without this resistor, closing the contactor would generate a large amount of inrush current causing the contacts to arc. This arcing can permanently weld the contacts in the "on" position. The inrush current from not pre-charging can also cause the contact tips to get pitted resulting in a poor connection and diminish vehicle performance."

"A coil spike suppression diode is a protection device across the contactor coil. Energizing the contactor coil creates a magnetic field that forces the solenoid arm to engage the contacts. When the contactor is turned off, the magnetic field collapses causing a back “voltage spike” that can damage the controller. The diode safely suppresses this energy."

"Note: Pre-Charge Resistors and Coil Spike Suppression Diodes are required with all Alltrax controllers but are not used with Curtis AC controllers or Sevcon controllers."

From electricmotorsport.com

baja bad boy

New Member
What i am asking is, I think my controller has been affected because I have been running it without a diode or resister and it doesn't need a key to run? Could this be the cause?