If I were to do this, I would go the old-school lead-acid deep-discharge marine battery route. They are safe enough to put in the basement or garage. How to do

If I were to do this, I would go the old-school lead-acid deep-discharge marine battery route. They are safe enough to put in the basement or garage. How to do this is well understood and doable by hackers. Lithium batteries are pretty scary. For example, https://en.wikipedia.org/wiki/Boeing_787_Dreamliner_battery_problems https://en.wikipedia.org/wiki/Boeing_787_Dreamliner_battery_... is pretty frightening.