I am sure many of you have seen Power Wheels vehicles and may have owned them for your children.  The original batteries can lose their power and need to be replaced.  Or you may pick them up cheap at a garage sale, usually with a dead battery.  My first jeep if bought new would be $280.  I got it at a garage sale for $10 and then spent $90 on an OEM 12v battery.  Original Power Wheels batteries are expensive.

I also picked up a quad for $10 that had two 6v batteries.  That was going to be $50 for each battery.  I found a power wheels website that does modifications.  I found a better 12v battery and instructions on how to rewire it...which I did.  The 12v battery was $27 plus $20 for shipping.  $50 cheaper, I can use my battery tender which won't overcharge the battery (like the Power Wheels Charger will do), and this has higher amp hours.

HERE is a video of my son on the quad with vid of the battery modification.