golf cart

Look for a dc/dc voltage converter and tap your whole bank so as to keep it balanced. You must be running a 48 volt Club Car? You would probably need an 80 down to 12.x or 13.x model. It will depend on what your charger is putting out but it could hit 58.xx depending on the charge profile. My 48 volt Lester cart charger regularly hits 61 volts. Before I would buy anything get a digital meter and monitor a charge cycle and see what the top voltage is before going into float. If the charge voltage stays under 60 than a 60 to 13.x model may be ok but 80 to 13.x will have you covered no matter what with some margin. If it's set up with Trojans it will probably see a daily charge of 59.2 and an equalize of 62 volts.

You may be able to look at your owners manual for the battery charger specs or get a model number off it to see what max voltage is. As Boon Docker also said, what are you going to power? Need proper amperage. Lighter socket is usually only 15 amps or so but.....