Bryan Martin writes:

http://www.backeastsolar.com/ Click on "Online Store" then "DC to DC
converters".

http://www.backeastsolar.com/pr_lvco...onverters.html

I went the marine-grade route for the DC-DC converter I use to power a
wheelchair computer.
http://www.jackrabbitmarine.com/prod...pID=682&type=0
My 4A model is in a small aluminum frame. I figure if it can withstand
a marine environment it can take my abuse. The 4 and 10A models are a
little cheaper (and lighter and smaller) than the 20A model from Back
East Solar.

--kyler