A fully charged 6v battery should be around 6.6-7v (depending on where the charger cuts off). If so, charge the 12v battery, and see what happens. You're going to destroy both batteries in a ...

A guide to super-charging your electrified Power Wheels. By Dan Roe Published: Dec 24, 2019 9:19 AM EST. Todd McLellan. ... You could drop in a Power Wheels brand 6-volt battery, ...