Iím testing mine now with a simple zener regulator. Looks like this:
(battery +)---[ I< zener ]---/\/\/\/---(battery -)
Iím using a 6.8v 5watt zener diode but even a 1 watt should be enough. The resistor is a 10ohm, 10watt power resistor but a 1 watt resistor should be enough. If you use the 5watt zener, you might just use it by itself across the battery to provide a hard voltage clamp.
(battery +)---[ I< zener ]---(battery -)
The output of the white lighting wire is minimal. If you use a 6V lead acid battery, you probably do not need a regulator, just a rectifier diode to charge the battery.