other batteries
there are also foamed lead acid batteries that would help. After being on the waiting list for 2 years I was told there would be no public availability. Production goes first to the military, next to heavy truck companies (the batteries are strong enough that trucks don't need to be kept idling for heat and power) and to OEMs that wanted small powerful batteries for things like lawn and garden equipment. I figured it out at half the weight per unit of stored power compared to standard lead acid batteries.