As a Stampede owner, I thought I would share this with you
My battery charger needs a 12V source, I used my car battery, but it's not fun in winter when it's -20°F!
So I dig some web site on how to convert an old ATX power supply and followed the how-to, here's my result:
It gives 8 Amp on the +12V which is enough for my 4A charger.
It costed me less than $10 in parts I guess.
I made a summary on my web page with links to others websites: