Originally Posted by ridge_racer
Hummm...that is a fair amount of imbalance. Have you checked the IR of the weak cell again.? I have 2 smaller 2s1p 800mah packs for my Uflys that are 30c and they never are more than .01v difference per cell even after 2 weeks on storage charge.
I haven't re-checked the IR's, but I will and report back.
Originally Posted by alexf1852
Could it be the parallel charging that is causing this? I read of similar reports with other brands when parallel charging on another forum.
I have several 6S 3000 to 3300 mah 30C lipos with balance of within 0.03V always after discharge. I don't parallel charge.
I don't believe so. I've been parallel charging for almost 2 years, with many many packs and have never seen anything like this before. One downside to parallel charging can be that it could hide a bad cell if you aren't on top of checking your cells individually. I'm kind of a fanatic about caring for my packs, so I'm always checking my packs, after charge, after flight, before charging, and after storage, even if it's only a couple of days. This one pack, no matter what I do to it, after a few days that one cell drops dramatically.
The fact that this pack, and this specific cell came with a fair amount of imbalance is the real issue. I was able to balance it by charging that one cell as a 1S to match the others. And now, after only 10 or so cycles, if that, it's showing the same amount of imbalance even after it's been balanced. I think it's just a bad cell, it still works, and seems to put out power still, but for how long is the question. I'd say it will eventually fail before the other cells do, but how long that is, and how many cycles is anyone's guess.