I know I'm late to the party with this post but I think it's worth mentioning. I used to use two 8 volt batteries to run my headlights and taillights. A problem occurs when you use the headlights just after taking the battery pack off charge. Immediately after charging an individual battery may have a temporary 9+ volt surface charge, for two batteries that adds up to 18 volts or more. My headlights didn't like that and both burned out when I took the cart off charge and turned on the headlights. To get around that I would run the cart without headlights for a brief period before I turned them on, not a good solution. Eventually I bought a 48 to 12 volt converter.
JerryK