Controller basics: what the amps mean, why it gets hot, and reading an error code

The controller turns battery DC into three-phase power for the motor. Its max amps × battery volts = peak watts (a 22A controller on 48V is about 1,000 W peak). Bigger controller than the motor is rated for = heat and burnt windings on long hills. Mount it where air moves over it; inside a sealed bag it cooks.

Error codes on the display are usually: motor hall sensor fault (check the 5-wire hall plug, water in it), throttle fault (throttle not at zero on power-up, or a short), brake fault (a brake sensor stuck on), communication (display cable). Unplug everything, dry it, plug it back in one at a time. The hall sensor plug is the one that corrodes.