Hi mat,I have a 2002 ezgo golf cart that I have the following upgrades:
400 amp controller, high amp forward-reverse, 4 gauge wiring and 6:1 gear ratio rear end.
I can easily run 28 mph but need more power if starting on hills.
My question- Can I add one 6 volt battery to make 42 volts and also will my 36 volt charger work?
What you need for improving hill starting capability is more torque. Starting torque for these types of controllers is proportional to the current rating; 400 Amps in your case. Raising the battery voltage will not affect that.
The controller may or may not work with the extra 6 Volts. The charger would not fully charge the pack with the added battery.
I recommend you take a voltage and current measurement on the hill condition to see what is really happening with the battery and at the motor before doing any modifications.