Powering a DSLR from a 12v battery pack

[telemarker]

I have an ACK-2E AC power supply for my 20D and wondering about using the DR-400 part with a step down from a 12v jumper battery for imaging at remote locations. Specifically, I was wondering whether a Nokia car charger could be used as I have a few of these lying around. A multimeter indicates it gives two voltages (6.7 and 8.3 volts) when hooked up to a jumper battery. Anyone tried this, or anyone with sufficient knowledge care to pooh pooh the idea.

[Merlin66]

I was considering something similar for my 300D... hadn't thought of a 12V phone charger!!
I need around 7.5V at the battery, so I'd say your Nokia solution at 8.3V would be well worth trying.
If you make up a connector in the leads to the DR-400, you should be able to switch between the AC and battery/ Nokia options.

[Lumen Miner]

Depending on the draw current of your device, I would say a resistor maybe in order. Just to be on the safe side. Although, caution is my best option.