I charge my still camera stuff and power my netbook using a cheap inverter. Lower current ones plug into your 12v accy/lighter and deliver plenty to drive a battery charger.
Using an EX3 I did a long interval recording of a 13 million pound dragline crane “walking” across a four lane highway on a temporary man-made cross road in -40F (well, that’s -40C too) at about a tenth of a mile per hour. I parked the truck sideways in the median, rolled down the back window, and shot from the truck due to wind and cold. I ran that EX3 on the inverter for the entire time, a couple of hours at least, while I ran around and shot the run-n-gun stuff with the EX1 outside. Coldest shoot I ever had. My Canon still camera batteries froze up frequently but the Sony batteries had no issues.
For shooting aurora borealis I even bring a 100′ extension cord reel so I can drive a set of Logitech speakers to provide mood music. 🙂 This is all from a relatively small inverter; if you wanted to drive a lot of equipment, you could always get a higher wattage model that connects directly to the vehicle battery.
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