| I currently use 7.2 Volt 900mah batteries. Can I use 7.2 Volt | 1800mah, or will that "fry" it. Is it the voltage that is important, | and the "mah" relates to how long the battery will last? Any advise | appreciated. Regards
Use these batteries in what?
You are right -- it's voltage of the battery, rather than the capacity that really matters when it comes to burning out the ESC and motor, and the `mah' (miliamp hours) basically tells you how long the battery will last, but it's not that simple.
If the new battery has twice the capacity, it may weigh twice as much. So the motor in the plane will have to work harder to keep it going, and you keeping the throttle at full the whole time may burn up the motor. And with a lower internal resistance as suggested by another poster, it could put out somewhat more voltage as well. And if your flights last longer, that may not give the motor a chance to cool off, again shortening it's lifespan.
And it's entirely possible that the bigger battery will weigh too much for the plane to fly at all. You can't just throw a bigger battery pack into a plane in many cases.