This seems like building more batteries (just, with extra hardware).
An EV could be good for this sort of thing, but I guess it would have to sit around at less than 100% charge, to have the capacity.
An EV could be good for this sort of thing, but I guess it would have to sit around at less than 100% charge, to have the capacity.
<absolute max that you are willing to charge your battery to> - <minimum that you are willing have your battery sitting at>