--That will tell you a lot about your battery and your meter. It should register a peak voltage after charging, drop rapidly to some level, then provide power at a more constant voltage for the useful duration. Then the voltage will begin to drop fast. It is that point, the voltage at which you see the voltage drop quickly, that you should never reach while in the air.--

So that voltage at which it drops quickly is different for every pack then and I just need to do these tests with each pack I buy?