It seems running two golf cart batteries in a series is the way to fill my two battery compartments (when I get them). I see they run slightly larger than a more typical 12 volt. I assume these fit th...
The best "bang for the buck" in golf cart batteries are at Costco or Sams Club.
3 of the best lithium ion cells (size 18650) will provide about 12V for 3 amp hours and cost about $20. For 242 Ah you would need about 80 sets of 3 or $1,600. Then you would have to assemble the pack. You would also need a special charger.