Originally Posted by hanknmorgan
Hello. I just purchased a used RC12l4 and am new to the forums here. I have a few questions. First is the ESC wiring. The car came with a GM sx9 purple ESC. The wiring was kind of wierd on it and had one of the battery and motor wires soldered together. Meaning that there were only 3 wires soldered to the ESC instead of 4. It also had a black capicitor soldered inline on the leads. All that seemed wierd, so I soldered new deans wires to everything, but I was wondering what the capacitor and funny wiring was for?
I hope that makes sense. Also, does anyone have any good recommendations for an asphalt setup. There is a local track at hobbytown that I would like to get into racing at.
Lastly, I was wondering where I should order bearings from for the rc12l4. One of my front wheels has alot of wobble and a couple of my diff bearings are shot.
I didn't see a full reply to this:
The SX9 only has 3 solder tabs on it anyway. The motor and speedo both need a connection to the batteries, it is better to have a solid piece between motor and cells and t the speedo wire onto it. The speedo does NOT need a large +ve supply as it only needs enough current to control itself and run the BEC circuit. The speedo switches the -ve on and off very fast to control the motor speed/power.
The capacitor is to smooth the voltage entering the speedo and gives a little more punch, when you go hard on the gas the electrical current is large and the batteries voltages 'sags' because of their internal resistance and the wires resistance, the capacitor stores a little energy to reduce this as it can give that energy out fast giving the cells an easier time.
If you use brakes a lot you may need a schottky diode too. This protects the speedo. The SX9 is pretty good, nice and small and has won some 12th world championships!
For best efficiency solder direct to the motor and cells, if not use 4mm 'corrally' type connectors as they have less resistance than deans and you can also end up with less wiring.