Bad lipo cell but IR is okay?

[jkflow]

It's not a charger issue and @Just a hobby it's not the same issue.
@Just a hobby you simply have dirty connectors, cleaning will fix it.
@Hector_Fisher you have a contaminated cell i.e. a manufacturing defect. Nothing wrong with your charger. You can happily use this lipo if you limit yourself to 4.1V charging, or get a replacement. Will be fine if you stay in the 4.1V range, just annoying.
Trying to charge at higher voltage will just result in extra heat.

 

[Just a hobby]

It's not a charger issue and @Just a hobby it's not the same issue.
@Just a hobby you simply have dirty connectors, cleaning will fix it.
@Hector_Fisher you have a contaminated cell i.e. a manufacturing defect. Nothing wrong with your charger. You can happily use this lipo if you limit yourself to 4.1V charging, or get a replacement. Will be fine if you stay in the 4.1V range, just annoying.
Trying to charge at higher voltage will just result in extra heat.

Chargers I own are good. It's the balance connectors, I don't use the loose one anymore. I one lipo that has a tendency to slightly swell at 1c. When I drop the charger 1amp no swelling. The lipo is also 3 years old good power and normal run time. Bad cells happen. Hopefully the warranty can be used in this case, I hope so!! The one balance wire extension was from Amazon, right from the start it had a problem. Even affected the ohms reading.

 

[LibertyMKiii]

Any thoughts on why this lipo can't hit 4.2v on one of its cells when charging at 1c? This is the 4th or 5th time I've charged this, on varying channels on my charger, and after an hour or two of charging, the last cell still sits at 4.1v. I usually have to discharge 500mah, then finish charging at 2 amps to get 4.2v on all cells. No problems with any of my other lipos.

My garage is warm (85F), but the lipo is observably warm right after charging. I just don't get it. Sure, IR is slightly higher on one cell, but no where near as bad as one of my 3s zeee's (18, 5, 4 mOhms). And that zeee still charges in 45 minutes, and doesn't get warm. So what's going on here?
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I have seen this on one of my $180 lipos where I had the positive and negative leads touch for a second. It damaged one of the cells.
Painful $$$ mistake I made. That one damaged cell is always down by a tenth of a volt. It seems that the last cell in the series is the one that gets hit the hardest....

 

[Hector_Fisher]

I have lots of suspect ideas about what it could be; some of them mentioned so far. I didn't have time today, but plan to attempt some full charges at 1amp, 2amp, etc to see when/if that triggers something different. If different at lower amp charging, i might still have a working lipo, albeit a slow charging one.

To that point: we typically refer to IR as one of the best measurements of the lipo's health. When we have a "bad" cell, it's generally noticeable in charging/discharging or IR readings. In this case, with the IR results providing some--shall we we say misleading--data, how would i determine when this lipo is ready for retirement? (will still attempt to get ahold of CNHL for warranty) Obviously heat during charging sends me red flags, but if the problem is sorted out by charging slowly, the lipo doesn't have heat issues on discharges, and the IR appears to be fine, then on what grounds would you determine a lipo usable (within specific parameters, such a charge limit or charge voltage limit) vs an unknown quantity and not worth the risk?

 

[Just a hobby]

I have seen this on one of my $180 lipos where I had the positive and negative leads touch for a second. It damaged one of the cells.
Painful $$$ mistake I made. That one damaged cell is always down by a tenth of a volt. It seems that the last cell in the series is the one that gets hit the

I have lots of suspect ideas about what it could be; some of them mentioned so far. I didn't have time today, but plan to attempt some full charges at 1amp, 2amp, etc to see when/if that triggers something different. If different at lower amp charging, i might still have a working lipo, albeit a slow charging one.

To that point: we typically refer to IR as one of the best measurements of the lipo's health. When we have a "bad" cell, it's generally noticeable in charging/discharging or IR readings. In this case, with the IR results providing some--shall we we say misleading--data, how would i determine when this lipo is ready for retirement? (will still attempt to get ahold of CNHL for warranty) Obviously heat during charging sends me red flags, but if the problem is sorted out by charging slowly, the lipo doesn't have heat issues on discharges, and the IR appears to be fine, then on what grounds would you determine a lipo usable (within specific parameters, such a charge limit or charge voltage limit) vs an unknown quantity and not worth the risk?

Bad puffing and when a cell is off by, example 3s 4.05, 3.90 4.05. That lipo needs to be tossed. When numbers get this way off. I have 1 lipo at end of charge might look like this 4.20, 4.18, 4.20. I'll use it. At next charge I will charge to storage at 2 amps or less. And to full charge only at 4 amps for a 5200mAh. It Does get it to balance fully.

 

[Hector_Fisher]

I need smell-o-vision. Okay so first off, I don't plan on charging this lipo anymore. It's giving off a small I haven't smelled before.

I know some people have said to smell a "sweet smell" when lipos go bad, but this doesn't really smell sweet. NOTE: it could be I'm smelling the same smell everyone else is, I just don't describe it as sweet.

Can anyone describe the smell of lipo death to me? I'm 99% positive that's what I'm smelling, just want to get some more descriptors out there.