A quick calculator to work out how long a Lipo battery will last.

Measure the current drawn by the motor or motors with a wattmeter and note the maximum value of the current draw in Amps

Enter your battery capacity in milliamp Hours e.g 2200 mAh then enter the current draw

The value calculated is in minutes

The value would be if you fly at full throttle all the time, which you probably won’t. So if you use this as a starting value and find you still have 40% left in the battery then up your timer 20-30 seconds and check it on the next flight.

I usually don’t like to go below 20% as shown on my battery checker.

If the time evaluates to something like 5.07 minutes that means .07 of a minute. Which is 60 x .07 so about 4 seconds.