[J0SH44]

I just brought home a 'new to me' Powerwheels Kawasaki KFX w/ Monster Traction. No battery, so I would like to wire in three 6v12ah (possibly bigger ah--looks like there is a bit of room in there). Can I just cut off the stock connector and wire in the three 6v batteries in series (with a 40amp fuse) or does the extra voltage need to go in a certain place to avoid burning out any boards/relays? I have read a few different threads and I am still confused. I would like to avoid burning anything up--at least right away. This thread seems to imply that wiring the batteries together where the old 12 volt battery was wired in works fine: viewtopic.php?f=57&t=6083. But there is no long term report (at least a month out) to verify no extra damage to the boards or relays. Like Sea Stork says in the post I would want to keep the high/low button to help with the gears. Do I need to upgrade all the wiring as well to something heavier?

At some point I would love to go to 24 volts. If anyone has any information on what I would need to purchase to make that move I would be very appreciative as well. Would there be any advantage (speed or torque) to purchasing new motors while at 18volts?

Thanks in advance for the information