[yurtle]

Originally Posted by JohnnieB

Precharge resistor: Reduces the amount of arcing and pitting of the solenoids contacts. The controller contains several filter capacitors and if discharged, they will try to draw hundreds of amps the instant the solenoid contacts close. Problem is that solenoid contact don't close and stay closed instantly, they bounce a few times first, so you get arcing.

For safety reasons, the filter capacitors have have a bleeder network that will completely discharge them withing a few minutes of battery being disconnected (solenoid contacts opened). The precharge resistor bridges the solenoid contacts and keeps the filter capacitors charged almost to the battery pack voltage, so the inrush of amps through the closing solenoid contacts is minimized.

Suppression diode: The solenoid coil is a strong electromagnet. When the circuit that energizes it is broken, the magnetic filed collapses and by doing so a strong pulse of electric energy in the opposite polarity is generated and causes arcing at whichever set of switch contacts opened to de-energize the solenoid's coil. The diode routes the spike back into the coil rather than into the solenoid activation circuit.

The pedal switch is the switch that usually breaks the circuit, and its contacts are rather puny, so the diode extends the pedal switches useful lifespan.

Not thousands? Seriously...