Broken battery cell recovery

[InterFelix]

Hello,
I have a Phantom 4 Pro battery with a cell that has a severe undervoltage and therefore reports as broken when I put it in the drone.
The battery is long out of warranty (4 years old), so I have opened it to try and balance the cells with my balancer.
Now my problem is the following:
The phantom smart battery uses a small connector I have never seen before. Looks kind of like a miniature JST XH connector. There is a connector called JST SH with the correct pitch (1mm), but it does not have some features present on the connectors from the phantom smart battery (small plastic pins and corresponding notches to secure the connector in place.
Has someone attempted this before and can help me?

 

[Steve7777]

Sadly, balancing up the individual cells is unlikely to recover the defective cell and the battery, at least, not in the long-term. The chances are that the cell is just worn out and will continue to lose charge a lot faster than the other cells.

I also fly racing drones, so I have loads of non-intelligent lipo batteries ranging from 1 to 6-cell. Sometimes I get batteries which go bad owing to just one defective cell, with the cell even dropping to below the 3v level at which my chargers will recognise the lipo for balance-charging. There are simple ways around that (which I won't go into here) but even if I do manage to get all the cells balance-charged by my charger, the next day - or when I next fly, the voltage on the defective cell will again quickly collapse, risking a nasty plummeting-to-earth if in flight. It may even drop back below 3-volts within a few hours without even being flown. Sorry - but IMHO, you're probably just wasting your time, however much fun it may be...

If I have the time, what I usually do is remove the defective cell completely and make a 4-cell battery into a 3, or a 3-cell battery into a 2 - and so on... Intelligent flight batteries are just a little bit more complicated and 'fussy' than that, unfortunately...

Good luck anyway!