Cory, when you said kids battery were you talking about the one out of the 1/18 Ruckus? The esc's in those burn up really easy. I went through 3 of them before I went brushless. The $20 ebay motor and esc work great in that little bugger btw. You just need a RX/TX.

The stock power system in that truck sucks big floppy donkey dick. If you want to upgrade it this is similar to what I put in mine. The esc I bought only runs on lipos and is not available anymore.

Motor and esc http://www.ebay.com/itm/Hot-2435-480...YAAOSwP~tW2P2~ The esc is not waterproof but thats easy to fix with a ballon or liquid tape or plasti dip.

Pinion http://www.ebay.com/itm/Pinion-Gear-...sAAOSwgmJXyOme

RX/TX http://www.ebay.com/itm/Flysky-FS-GT...kAAOSwEeFVGPWA

If you want some Lipos you could give these a try http://www.ebay.com/itm/162172021091 As a warning these batteries are kind of hit or miss as far as quality goes, some people love them and have no issues other people have them last only a few cycles.

Just throwing some ideas out there.