Years ago we bought several of these PowerWheels quads for our kids to ride around the backyard. Unfortuanatly these are 6 volt models without a lot of power. This works fine when the kids are 2-3 years old but when our 4 year old hit 60 pounds they no longer have the juice to move him forward.
There is an easy solution to this problem, if you drive a 6 volt motor with 12 volts it will run with WAY more torque. At the same time I thought this would be a good opertunity to increase the battery size so they could use them for a few straight hours before they would need a recharge.
Now as you can see in the photo to the left there is not a lot of space for a larger battery so some surgery will need to take place.
The photo on thr right shows after the plastic had been removed with the dremel and the new gel cell placed in. I then charge the 12 volt gel cell with a car battery charger that supports gel cell.
Once completed my 6o pound boy can drive it uphill at a fair rate of speed and my ligher son can catwalk the quad by leaning backward and hitting the gas.
Now there is a word of caution before attempting this mod. This will reduce the life of the motor and gears. I have now done this to two of our quads and stripped out the inside of the plastic wheels after my sons crossed about the 75 pound mark. This can be easily fixed by drilling a hole through the axel and running a pin through it and into the wheel. It helps to bend the pin to stop it from sliding back through the axel.