Maybe a little silly question, but when I land after about 8 and a half minutes flight, then each of my batteries is at 14% (22,24v) but when they have bin laying for some time, then they come up to 33% (22,78v) Is this normal? And which one should I trust? Have a little difficult to find out how much I can drain my batteries, and therefore how long I can fly.... It is all Tattu 10000mAh
Yes they will 'bounce" back up. If you check your inflight voltage it is probably lower than 22.24. Land and check them you art at 22.24. Hours later they may creep up a bit higher.
Batteries "at rest" will report differently than batteries under load. The best way to determine the actual percentage of your batteries' consumption is to take note of the number of milliamps your charger puts back into each battery when it's done with the charge cycle. For example, you may find that a eight minute flight results in your 10000mAh LiPos getting 6000mA put back in during their charge cycle. Unfortunately, the relationship between the voltage and the current in your batteries is inexact when you're in the air, so you have to learn your batteries' personality. That is the nature of this stuff. As for me, I generally consider my flight mostly over as my voltage goes below 21.8V in the air, and I generally try to land at about 21.0V. But I've pushed that farther in some cases. I know my batteries pretty well, and they're very reliable.
I could be them Ions. I think it's called ionic charge. Check out this video explaining IR, and at about 6 minutes in he attempts to explain the mysterious return of voltage (but as Steve says, the truth is in the amps) .
Steve Maller, when you land at 21.0V, what is the % and volt when you measure right after? I'm just afraid that I crush my batteries, when they indicate 14% right after landing, though they come back up again.
I don't pay any attention to the voltmeter readings. All I care about is the charger's measure of the number of mA replaced, which is generally 7000-8000. That's the sweet spot.