ct420 is right. You cannot calculate watts based on the batteries capacity rating.

mAH stands for milliamp hours. A milliamp hour is the amount of charge removed from the battery after drawing 1 milliamp of current for 1 hour.

You can do a general calculation on runtime if you take your battery capacity and divide it by your amp draw.

E.g 2200 mAh battery discharged at 2.2 amps (2200 mA) would last one hour. Discharged at 4.4 amps, it would last half an hour.

Here's a quck sample (note you need to use the mA (not Amp) value

2200 mAh / 25000 milliamps (25 Amps) = 0.088

To get the runtime in minutes, simply multiply by 60.

0.088 x 60 minutes = 5.28 minutes

The full formula is: (mAh / C) x 60 = Time in minutes.

Naturally, this formula assumes constant current draw. Since that isn't the case for our models (amp draw varies wildly depending on what you're doing), this basically just gives you a rough estimate on the runtime you can expect. In most cases, the actual runtime will probably be more than what you get using this calculation.


The reason most people don't go to 4S is because of expense. Batteries are more expensive, the controllers are more expensive, and you need a motor that won't cook on the extra voltage as well, and these motors are typically pretty pricey.