Batteries capacity and low voltage behaviour

[chiloschista]

Hi ensemble,



after a very long flight, where I discharged the battery to about 13.8V I noticed the charger did charge 6300mAh. So what?

I did a full discharge cycle then and discharged the battery at 1.5A down to 3.3V/cell.

Guess what? I got 6449mAh!

Ok it was a discharge at very low C rate, but anyway ...



I checked again the label and yes, they say 5400mAh.

So a plus point to Yuneec which delivers batteries with well matching specs and overpassing them by a good 18%



About behaviour at about 14.3 the controller start to vibrate and shows a warning: the copter will set at max altitude of 60m.

At about 14.1 (not sure about that), the copter will forced to land. The pilot can force it to stay up and try to bring it home, but this is very dangerous, as if the battery goes to low it will land hardly (or crash). Can be used to adjust the landing spot.



Anyway, my philosophy is that at 14.5V is time to land and don't go under 14.4V, which still gives a good margin to manage a safe RTH and landing.



Best regards,

Ric

 

[Rayray]

Good post, thanks.

 

[David Wilson]

You are correct. Some people are a little too cautious and land at 15.0 or sooner, but that cuts too deeply into my flying time. The one advantage is a quick re-charge.

 

[Steve Carr]

I generally land at 14.7 and after shutting down the voltage rebounds to around 15.1. I do get fairly fast recharge at that voltage.

 

[chiloschista]

Well I have to say that I don't push it to the limits at any cost. If the flight is done I land. Those were tests to have a safety margin knowledge, because I like to know exactly what happens and why.
Ric

 

[Steve Carr]

Well I have to say that I don't push it to the limits at any cost. If the flight is done I land. Those were tests to have a safety margin knowledge, because I like to know exactly what happens and why.
Ric

Good Plan!

 

[chiloschista]

Thanks = : D
Ah, and I mean voltage under load.