[squatch81]

I have a 2009 Prius that has a blown head gasket - approx. $2200 to repair.
It still runs fine, but it blows gases from a cylinder into the water jacket and blows the coolant out. It goes about 30 miles before it overheats.
Most of our errands are about 5 miles round trip, but with antifreeze costing 4 times as much as gasoline it is expensive to drive.
I understand one can force a Prius into "out of gas" mode by installing a switch in series with the fuel pump fuse, but that will only get me a mile or so at speeds up to about 50 mph. What if I were to put 16 12 volt lead acid batteries in the back and wired the string in parallel (via a contactor) with the factory battery pack? How big of batteries would I need to get 10 - 15 mile range? Would U1 garden tractor batteries do it? Or am I nutz for even considering doing this?