A 50kW Tesla (model 3) battery is what, roughly 700lb and provides a range of ~220m miles if I'm not mistaken? Batteries of this size are simply not portable, nor are they cost effective to keep 8 in case of emergency. I live in an area that has occasional hurricanes and when one is threatening the area I go fill up 8 5 gallon gas containers and store them in the yard. Assuming the storm passes without major damage (power outages, etc.) we'll use that fuel to fill our vehicles' gas tanks. There is no equivalent of this in this new-fangled electric world. Until batteries become smaller, light and a hell of a lot cheaper, I'll be sitting on the sidelines.