Been pondering this a while...I have a 10,900 6S pack here, and regularly put in "9000" on the charger. I try to land between 3.65 and 3.7V.
If I'm putting in "9000" whatsits in, am I leaving the landing too late?
I ask because I have a 4,000 Turnigy pack which I also land at 3.7V on, but it's puffed slightly (I've never gone below 3.7 and always charged at 1C and balanced).
I'm concerned that the same fate awaits my - rather expensive - 10,900, even though I've been very diligent about battery care.
A second question - when is the best time to charge? Normally I charge the morning of the flight, leaving the battery to cool overnight. However, I have left batteries with a full 4.2V for 1-2 weeks on occasion. What's the advantage of the "storage" setting (3.8v?) on the charger?
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LiPo's lose about 1.2% capacity per month @ 25°C if kept unused at full charge for the whole month. Storage charge sets the pack to about half charged which LiPo's prefer for long periods.
Puffing is a funny thing, some cells don't puff ever, others puff even when treated with care. Landing at 3.7v under load is very safe, the reason being that cells are never perfectly balanced so while two may be at 3.4V on a 3 cell pack the other can be at 3.0V, which equals 9.8V - still 'OK' for a 3 cell (>9V) but the cell at 3.0V is at borderline irreparable voltage. 2.85V is cell suicide.
Charge just before flight if possible, a slightly warm battery will perform better too. But charging the night before is also fine.
(9000mAh from 10900mAh is 83% so a little over recommended maximum discharge, 80% is recommended for longevity.)
P.S. I designed an Android app to work all this out: Playstore link