Hey, better check your theory with a wattmeter, the 7AH 12 gel cells like the one i have in my flight box won't hold the voltage when placed under the heavy load of a starter, this is why your lawn tractor battery will spin it and it will probably stay at 12V, and your hint is not a hint becuase when you put more volts to a DC electric motor it will also increase the amperage which means more power.