Here's a cell phone power pack that's 25k mA and is 3"x6"x1/2". It'll give more than 6 hrs of heat running on high, many more hours on lower settings. There are many 10k packs that are half the size but give proportionally fewer hours of heat and don't cost much less.
Correct me if my math is off, but 25k mAh is 25 amp hrs, is it not? Times 5V = 125 watt hrs. A 5AH Milwaukee battery is 5A. Times 18v = 90 watt hrs. Those little power banks pack have a lot of juice.
POWER PACK
