My 3 batteries only have 5 charges each on them and when I recharge them. On a full charge all I get out of them is 96% and dropping. Is this normal? How do you get them back to recharging at 100%?
What’s likely happening is that one cell in the series string of your battery pack is out of tolerance and during charge cycle reaching HVC (high voltage cutoff) before the other cells in the pack.
Here’s a visual of a 20S battery pack with voltage graph of each cell.
They’re pictured in close agreement but just imagine if one cell begins losing capacity which in turn would cause it to fill-up before the others?
Now imagine charging this pack, the majority cells reaching 4V but that one compromised cell now hits 4.2V. The BMS will cutoff charging and the practical result is that you won’t have as much overall charge available from the pack.
I dunno P2/P3 battery packs - in the regular RC Lipo world we would just use a balance charger to bring all the cells back into reasonable balance. But once cells start getting way out of balance, it’s gonna be a losing cause to keep up with ‘em. You need to be able to test IR and run true capacity tests to really know for certain.
IMO, the best thing people can do to prevent this imbalance is to avoid deep discharging your battery pack. Once you reach around 50% indicated, bring it on in. Pushing it further into low voltage regions can really propagate cell imbalance. Just not worth the potential irreversible damage that can be caused to the battery pack.
Buy an extra pack and between them fly as much as you do with one. But the difference is that they’ll last several years or more rather than being fubar within a few weeks/months.