Any sealed lead acid or car battery will work, as long as it supplies at least 12V or so...
I've been using old UPS batteries (30 lbs each, but last a whole race weekend) I got from work after they replaced them. They're old and not in peak condition, but they still last enough for me...
Otherwise, car battery is fine too.. why is it not charging? Does it say Power Supply Low, or does it just not work at all? It should turn on even off of the battery pack you connect it to, enough to give you a message of sorts.
BTW, what's the latest BIOS they on? I have 1.000c.. any news on future upgrades?
Does anyone else find that once in a while that my RPM count doubles when testing a motor?
It's a wicked charger nonetheless.. I bought one a few months ago, and I just won one at a race prize draw! I can now charge and break in and run motors at the same time, and I'm sure my SLA batteries will keep them running...
Tried my Duratrax Intellipeak power supply (the wall-wart) and it didn't do so well.. had enough voltage, but false peaked on my packs waaaaay before they were even warm.. ohwell..