What determines the operating voltage of an esc? If an ESC is rated for 8.4 volts and 100 amps why couldn't it be used at 12 volts and say 50 amps? In other words, does it absolutely have to not exceed 8.4 volts?
Any help would be appreciated.

I'm no electrics expert, but I think its because the fets in the esc have a maximum rated voltage.

Steven Vaccaro
www.OffshoreElectrics.com

avator,
Very simply, because the components used to make the ESC have a maximum voltage rating. If you exceed this rating (by more than just a little bit) several 'odd' things can happen depending on which part or component breaks down. Usually, the result is 'letting' all the smoke out of a part (burning the little bugger up) and that means a destroyed ESC. Voltage can be compared to water pressure. If your water system is rated for 20 pounds pressure and 50 gallons per minute water flow (flow = current), and you put 100 pounds of pressure on it, look for water on your floors. Even if there's only 20 gallons per minute flowing.
- 'Doc

Thanks for the info, I was hoping to get away with using 2- 8.4 volt esc's in a tank with a 12 volt power supply that I already have. Oh well, guess I'll have to dip into the hobby fund.