Hella type Switch Conversion
You can purchase this type switch at any Kragen autoparts store. It is rated at 300 Amps but it has a key that must be in place when turned on. This key could easily be knocked out during a battle so it must be modified. This modification allows you to turn the switch on and off with a regular flathead screwdriver.

Unmodified switch                    Cut key in half


Heat screwdriver   Insert into lower half of key


Ready to assemble         Cover bracket      Complete conversion

I have only given an outline for this conversion. If you have done enough research up to this point all the details should fall into place for you. Do your homework, search the many web pages out there and build a killer BattleBot.