All you really need is a simple cheap resistor. Unfortunately I don't
know the current draw on this.... but assuming about 20ma, you will need
to drop 8 volts; so you will need a 300-500 ohm resistor. I would use a
resistor that can handle 1 or 2 watts.

Dave Plowman (News) wrote:
In article
,
wrote:

I have an offroad trailer on which I want to change the existing 12
volt tube lights to accomodate led lights .the led lights run off a
4 volt rechargable battery how/what is the best way to change the
voltage from 12v to 4v on each set of lights there are 4 sets in
different areas I need to change the lights to accomodate the 12
voltage


Do a Google for LED drivers. There are ones around which will work over a
wide range of voltages. Ready made and circuits you can build yourself.
But for maximum efficiency you might have to go back to basics rather than
adapt your existing ones.

But if all you want is working light stick with fluorescent. It's more
efficient than LED at the moment.