Car batteries are seriously underrated as an off-grid power source. They can be charged in a day or less with low power alternative energy, even a 12v solar panel or smaller, and can power electronics for months once charged. Including lights, hot plates, laptop/phone/4gwifi, and so on. They can also be wired in sequence to create large battery banks to power houses for extended periods of time. Would be interesting to use in combination with a dugout or sturdy bushcraft shelter. I ran the math on the electrical usage, and a single car battery can power my pc and monitor for months on a single charge.