Do You need a switching regulator that converts the high volts and low current >into< low volts and high current?GM forum memeber Monkey Magic put me onto these.
http://www.ebay.com.au/itm/DC-to-DC-Converter-VKA60MS03-1-48V-3-3V-12A-out-Nice-/370102917617?pt=LH_DefaultDomain_0&hash=item562bda59f1They are idiot proof and totally isolated from input to output they has a safety mechanism that kicks in if you muck up the fine adjustment. They wont output over 3.7v +trim @ adj <<< I think.
Can take up to 72v input, they are tiny in size too. I got mine to output 3.5v and is perfect for leds. With a 48v system and heat sink glue this to a good hunk of aluminium you can easily output 10 amps @ 3.5v.
It draws about .100ma from my pack to power a 1amp lighting system. Leaving this on over night or the next wont kill your pack. I could run my lights for 150 hours with this regulator.
However, with a linear regulator, you have to provide the current the light draws. And @ 1A the linear reg will flatten flat in 12 hours.
Imagine a 35 watt led light system on your bike.
a 35 watt led ststem would draw approx one amp from a 48v pack.
This light system I ran off this converter was 16 watts.
The big light in the middle fell sacrafice to kids touching little fingers, they picked the lens off. But still the two 3 watt torches is plenty enough. Almost as good as car lights.