Should I be worried about my lipo

[dadlifex3]

Battery is a hardcase Zee 7200mah 80c. Been using it since October 2020. Have not had any issues with it and it always balances fine when completed. This is the second in a row time I’ve noticed the one cell is much lower than the others. This just started two days ago. Should I been worried about it? Trash it?

 

[Twitchfast]

I would keep an eye on it, but that's not far enough of a deviation to be a concern imo.

 

[GraniteFox]

agree. not a big concern. If it performs ok and looks ok (not puffing) just keep running it. If you see it get worse over time then the end might be near.

 

[dadlifex3]

Ok, thank you both for the quick reply. Will continue to monitor it. I’m in the process of balance charging it to storage voltage now. So far all cells are the same at 3.84v. Usually take off the charger at 3.90v per cell. After it settles a bit it rests around 3.87v.

 

[jondilly1974]

Definitely something to keep an eye on. But not really in the danger zone yet

 

[Warby]

I use worse

 

[dadlifex3]

Definitely something to keep an eye on. But not really in the danger zone yet

What would be the danger zone to look for? Being hardcase it would be hard to see puffing unless it was enough to split the case.

 

[jondilly1974]

What would be the danger zone to look for? Being hardcase it would be hard to see puffing unless it was enough to split the case.

Excessive heat, swelling, or more voltage loss

 

[arrmadillo]

I would still use it, who knows it could bounce back.

 

[dadlifex3]

Good deal. I’ll keep an eye out for those conditions. After every bash, 20-30 mins, I keep track of all the temps. Battery is usually 120°-125°.

 

[dadlifex3]

So, the same cell has been dipping lower than the others still. Today all were 3.4ish at cutoff but the one cell was 3.01. Should I try to balance it or scrap it? Normally it always balances back and runs just fine.

 

[dadlifex3]

This is after it has settled for about an hour to cool down and then put on the charger.

20 mins into the charge and they’re all even

 

[dadlifex3]

62 minutes into the charge

 

[SrC]

Cell # 4 is probably done if not close to it. What are the IR's for each cell? Can you test for that?

 

[dadlifex3]

Cell # 4 is probably done if not close to it. What are the IR's for each cell? Can you test for that?

What does IR cell mean?

 

[SrC]

"Internal Resistance". Read in Ohms.
Any basic Lipo Checker will test IR's. Most chargers do this also. Maybe yours does?
IR's for each cell will show if your cells are getting tired or if damaged or bricked. All cells will have higher IR's as they age/ cycled more and more or even if one is damaged. This is normal. Basically the IR's should all be close. When new they are very low (2-10 Ohms of resistance) As they age they can shoot up to 50ohms and higher. A problem. When one or more cells deviates from the rest, the cells are considered not matched well enough. Performance decreases. Not storage charging them after a bash and letting them sit around like that contributes to Higher IR's. Conersely letting a fully charged lipo pack sit unused for very long creates higher IR's. I never let my lipos sit fully charged (4.2v/cell) for more than a day.) I discharge them to 3.8v/cell if I am finished bashing or I wrecked my rig and need to discharge remaining volts to 3.8v/cell.
Also, even storage charged at 3.8v/cell and never used for months on end will cause this. Resting volts of 3.8 will drop over time with non-use. So even if properly storage charged, over months, a lipo should be re-storage charged again if rarely used. Usually it wil take a few minutes to get it back to 3.8v This will promote its longevity. Hope this helps.

 

[dadlifex3]

the lipo checker I have does not have that option. I’ll check the manual for my charger to see if it does. Passport Ultra P2

I did balance charge it last night. The end result was as follows.

Cell 1 4.17
Cell 2 4.136
Cell 3 4.175
Cell 4 4.088
Total 16.56

 

[dadlifex3]

The charger had that option. This is what was displayed but I have no idea what I’m looking at.

 

[SrC]

the lipo checker I have does not have that option. I’ll check the manual for my charger to see if it does. Passport Ultra P2

I did balance charge it last night. The end result was as follows.

Cell 1 4.17
Cell 2 4.136
Cell 3 4.175
Cell 4 4.088
Total 16.56

All those cells are tired but # 4 is donefore. Buy a new lipo.
I see those IR reads on the charger in pix. But I am confused. Display says 3s lipo. Yet reading 4 cells????
Not familiar with your charger.

 

[dadlifex3]

All those cells are tired but # 4 is donefore. Buy a new lipo.
I see those IR reads on the charger in pix. But I am confused. Display says 3s lipo. Yet reading 4 cells????
Not familiar with your charger.

The bottom (3S) is for another battery to plugged in. The top is only reading the 4s in question.

Really hate that because this battery is just under a year old. Granted it’s not a super top quality battery.

So what is an acceptable IR reading?