My friend's son has a power wheels F1 car. he wanted to make it faster....
Started out a single 6 volt battery. Added 3 more 6 volts today. Ran 3 in series & one in parallel for a total of 18 Volts. In the pics I wa sonly test teh setup. I did not leave the connections like that.
Before on full speed at MAX it was just above walking speed. Now...GEEZE. Had trouble trying to catch him.. **** was funny. Had to keep in under the parking area because of the rain, so the vid is a bit dark.
The cool part is the batteries are only $3 each. I wonder how many I can run..LOL
In Aug for my sons birthday I am getting him a Esclade adding 6 batteries & a stereo.
I love doing crap like this.

 

this reminds me of the time i took the 18v battery from my cordless drill and mounted it on my 9v rc car. it ran like never before and 20min later never ran.