SO cell 2 need to be replace ?

Replacing only one cell will give you similar results.

All cells must be replaced if you want a normal working battery.

Seems better but always voltage drop. And after 10% charging the poor balance come back . SO cell 2 need to be replace ?

Sorry for late answer, no time this week to see the battery.

So here is the screenshot of the battery, balanced cell, and discharged 1 minutes 2A.

I will try to charge this time and see if disconnecting this time

Ok Thanks and yes i understand ( ohm law).

And for the tools when i say no solder tools for cells i mean no spot welding tools.  In deed i have solder station, hot air station, desoldering station, binocular microscope , Dc power supply, bench multimeter etc ans now laptop battery analyzer because before i just replace battery pack but right now i see too many battery locked just because unused or laptop unused because i think windows 10 not shutdown completely and the battery keep draining ans also the new cell very quick locked ( last exemple i have new thin hp laptop arrived from distributor with battery 0% not charging). So right now i prefer to check an repair. And of course i want to buy the needed tools. For that do you have an advice for the right tools ( spot welder, battery charger/discharger etc) ?

Thanks

( internal resistane if i understand correctly) is higher on cell 2 like the soft tell me but stangely it's the cell that keep better the voltage and when i check the battery this cell already have better voltage

There is no such a term as better voltage. Cell 2 just has higher voltage than cell 1 & 3 but this does not mean it's better.

Why? It's also connected to IR. A cell with high IR will also have lower capacity and bigger volatge drop/increase under load.

So since cell 2 has lower capacity it will also have higher voltage than cell 1 & 3 when charged in series.

Posted by: @eukal1

I have no tools to solder cell , i have to order it and pearhaps a charge / discharge tools for orne or two cells.

These are basic tools that every electronic repair shop must have, or even hobbyists at home.

But cells are not supposed to soldered but spot welded. Heat from soldering iron can degrade the chemistry composition or damage them.

Hello, ok thanks for answer. I have no tools to solder cell , i have to order it and pearhaps a charge / discharge tools for orne or two cells.

However is there a simple way to discharge only cells 2 whitout desoldering it ?

Another question you tell me the ir ( internal resistane if i understand correctly)  is higher on cell 2 like the soft tell me but stangely it's the cell that keep better the voltage and when i check the battery this cell already have better voltage. For understanding what is a good range of IR, a middle range or a bad range ?

Thanks

ps : ok for screenshot i wiil use this button next time thanks

In the laptop same problem little charging pause ( i ear the bip stop chargind and bip start charging ).

This is because of the cells imballance. Cell 2 reaches full charge voltage before cell 1 & 3 so chip stops charging.

Discharge cell 2 to the same volatge as cells 1 & 3 it has slightly higher IR but but you can still try.

After you ballance the cells leave them to rest atleast 1 hour after this go to discharge tab start discharging with 2 amps wait 1 minute and post results.

Also please use NLBA dedicated screenshot button to post screenshots.

So i have an Acer battery recognize by the tool but bad balance at first and impossible to charge.

I try reset but error code, after search and open the battery i found the chip is 8505 and not 8300, but when i reset status is same.

So next after research i see it could be the fuse, and right so i put little drop of low melt solder like is say in other post and bingo now i can reset and charge the battery.

There is always a poor balance but charging except little pause in charging ( and wave in graph)

and i decide to check in laptop after 20% charged.

In the laptop same problem little charging pause ( i ear the bip stop chargind and bip start charging ).

So my question is : Is this problem of stop and start charging is due to poor balance ? Maybe bad cell : I have check cell in right tab and it's confuse to me because the cell that appear to be poor is the cell that keep better the voltage and is at 3.9v.