Help! Increasing LiHV internal resistance

[jeansero]

Hello guys,

I have a problem with my LiHV battery. When I charge it it starts normally, voltage level is continuously increasing, and after it reaches around 4.2V on the cells, the first cell internal resistance jumpes and reaches lvl 122 mOhms, my all cells at the beggining level is (44, 8, 40) Ohms, but after this IR jump is (122, 8 40). I use some ballancing board and self made connectors to use my charger - maybe its the reason of slightly high resistance level, but it is not explaining why internal resistance rises only on first cell. I have few batteries and not all of them have this problem.
Also the reading is fake then - it says 3,8V on first cell, I noticed that when discharging, it back to primary resistance, when other cells have 4.2V, then the first one also shows 4.2V, even though at the beggining it was 3.8

Anyone seen something similar before?
I have no idea why it behaves like that.

 

[LitterBug]

How many cycles are on that pack? It is normal for batteries to degrade with time. If you have one cell not like the others, it is probably defective.

LB

 

[jeansero]

Its not too much cycles, few, but Im preety sure that it is like that form time I've received it. I've just back from the fly session and battery voltage dropped suddenly from 25% to 10%. I had to run on the street to catch the drone

 

[LitterBug]

Its not too much cycles, few, but Im preety sure that it is like that form time I've received it. I've just back from the fly session and battery voltage dropped suddenly from 25% to 10%. I had to run on the street to catch the drone

How low have you been letting the pack get? I try not to go < 20% on my packs. Beyond that, you are running the risk of damaging them.

 

[jeansero]

Hm, how come? This 10% (displayed by drone control system) is in around 3.8V (I've measured it right after landing) per cell, for LiHV battery discharge state is around 3,3V per cell, so why they get damaged? I thought they shouldnt when are used to this 3,3V per cell limit.

Btw today was my first day when I've got under 20% when flying.

 

[PsyBorg]

I have the same issue with my radio pack. I drain it to 11.6v obviously very low current draw not like a flight pack before charging. When It goes on the charger its shows once cell at near full and the other two cells just below 4v. I have tried cycling it a few times on my charger to get the cells to equilibrium which worked on any other new battery I had bought but this battery still has the same issue.

I will go on the assumption the internal circuitry is bad in some way either by poor quality or poor manufacturing. I do not worry too much on mine as its low current draw but you are using a flight pack and that will have heat issues in flight which is potentially volatile and very damaging. I would relegate that pack to goggle power or something low current draw or retire it.