The solution is a voltage reducer.  Voltage reducers come in many different configurations, capacities and prices.  This is a complex subject and you need some experience in 12VDC systems.  For the sake of simplicity I will speak of voltage in terms rounded to the nearest full volt.  (So if an 8V battery reads 8.13 volts its simply an 8V battery)

Golf car light kits and universal light kits are 12 volts.  So how do you get 12V from a 48V golf car that uses six 8V batteries.  You can't use one 8V battery its not enough and two 16V batteries in series is too much power. 

When choosing your reducer you need to consider what accessories you wish to power.

1. 12V lights only
2. 12V lights and an accessory port for your cell phone charger
3. 12V lights, accessory port, horn
4. All of the above and a radio

Options one through three only require a simple two battery voltage reducer.  Option four requires a six battery voltage reducer with a high amp output.

A two battery voltage reducer takes just two of the batteries in series and drops the voltage from 16V down to 12V.  Choose any two batteries in series for your input and your output will be 12V for the lights, horn and accessory port.

A six battery voltage reducer uses all batteries in series to drop 48V down to 12V.  Radios require the full battery pack reducer because radios require a constant 12V input.  A two battery reducer will have its output interrupted every time you step on the "go" pedal of your cart.  In other words with the radio on the cart standing still you start the cart forward and your radio cuts out using a two battery reducer.

This is a lengthy topic that could fill several pages with dozens of photos.  See my guides in the near future for exacting details and how to instructions with illustrations.