And I’m hoping for mild temperatures. It hit low to mid 80sF yesterday, so I was back in shorts and a t shirt. Still got a little sweaty in the late afternoon sun. With evenings around 70F it’s pretty nice right now. I want more.
Did my domestic bliss. Shave and haircut, laundry. Bit of cleaning. Did some more work on the golf cart. I think I might have figured out why it caught on fire. There is a solenoid that lets power (36vDC at 350A) through the electronic speed control to the motor. All the online vids talk about how important the resistor and diode are that SHOULD be across the solenoid. They mention fire if you get it wrong. The solenoid in the cart looks brand new and it doesn’t have the diode or resistor. I wonder if they replaced the solenoid but not the diode and resistor and burned the direction switch and ESC…
Usually a diode across a coil is just to prevent ‘back EMF’ current flow when the magnetic field collapses. I didn’t think that could lead to the kind of intense fire that happened in this cart, but maybe? Google says “yup”.
Why Diodes Matter on Golf Cart Solenoids
• Voltage Spoke Protection: When a solenoid coils de-energize, they release a sudden back-EMF (electromotive force) voltage spike. A flyback diode (or resistor/diode combination) is installed across the smaller activation terminals to absorb or redirect this back-voltage.
Consequences of a Missing Diode: Without this diode, the voltage spike feeds backward into the speed controller, which can fry the solid-state controller circuitry, weld the solenoid’s heavy contacts closed, or cause continuous high-current draw that melts wires and insulation.
Solenoid & Diode Comparison
Component / Condition—Primary Function—Risk if Missing or Damaged
Solenoid Diode–Suppresses voltage spikes/back-EMF when the coil turns off. Damages the motor speed controller or welds contacts.
Solenoid Resistor–Keeps a small pre-charge on the controller capacitors to reduce arcing. Can cause heavy arcing or main terminals to weld together.
$3 in missing parts caused a fire than led them to selling a $4000 cart for $300… if that’s what happened. No reason to replace the solenoid after the fire, because it clearly wasn’t going to run with the slagged direction selector switch so my theory is “they done F’d up.”
I’m doing a bit more of the body panel replacement than I initially thought I would because it’s much easier to put it in place when the ESC and switch are out. I’m also pretty confident that with the new parts it will work again. If I was less confident it would make more sense to be certain it runs before doing any other repairs.
So today I’ll continue with that project, do a couple of pickups, put up some more decor, and work the list a bit, if I have time. It’s only Tuesday.
Always be working. Stack.
nick