There are 3 ways to hook up any 12 volt lights etc to a 36 volt cart.
#1- Hook the lights to 2 batterys in your pack. Problems are that those batterys will be pulled lower than rest of pack and charging whole pack will NOT BRING WHOLE PACK BACK TO FULL CHARGED. Solution-is keep moving your leads around to different batterys or charge the two used batterys seperately with a 12 volt charger to try and keep charge levels together? Also be ready for major voltage drops whenever you hit pedal as power drops so low that lights etc will almost dim out?
#2-Install some type of voltage reduction to the WHOLE BATTERY PACK so draw down will be even. ( MUCH BETTER THAN ABOVE ) Same problem when you hit pedal though?
#3- Better yet install a separate 12 volt battery that will carry anything you might add later on, Radio, Sterio, Disc Players, Turn signals, Under lighting and etc.
I use a 12 volt handicapped scooter battery UB 12350 $ 55.00 that is small and can be mounted in any position because its sealed.
I hooked mine to a power outlet ( HD Marine Type Cigarette Lighter ) and charge this battery through it.
This is cheaper than a reducer and is NOT EFFECTED by golf Cart operation.