Good 4S BMS recommendations?

[msacco]

Hey guys, I've built a 4S lithium battery(rated at around 95,000 mah), but I'm having some issues with the charging balance.

A friend of mine which has some experience with that built the battery for me as I don't have a spot welder, and he also said that he put his own BMS and not the one which I had.
So the battery generally works really well, but I have a problem with the charging or general balance of the battery.

When charging, I have 2 cells that already reach 4.2V and even go beyond that(I think the BMS should stop charging at 4.25V, but I don't want to go higher than 4.2V), while the other 2 cells are at around 3.8V and 3.9V.

I'm not really sure what the issue is, is it an issue with the BMS? Something else?
I thought of trying to replace the BMS to a higher quality BMS if anyone knows of anything that's high quality. Also, if anyone in general has some ideas of things I could try to actually balance the battery, that would be great.

Thanks for the help.

[Dr_Ju_ju]

If you've got something similar to this https://www.ebay.co.uk/itm/4S-12V-30A-BMS-Li-ion-Cell-Battery-Balanced-18650-E-bike-UK-seller-UK-stock/324180327170 then the system should lessen the charging current when the particular battery has reached full charge, so check that your wiring is correct. 

I've used lower amperage versions of these boards, to balance the charging of lithium batteries, as used in hand power drills...  

[msacco]

8 minutes ago, Dr_Ju_ju said:

If you've got something similar to this https://www.ebay.co.uk/itm/4S-12V-30A-BMS-Li-ion-Cell-Battery-Balanced-18650-E-bike-UK-seller-UK-stock/324180327170 then the system should lessen the charging current when the particular battery has reached full charge, so check that your wiring is correct. 

I've used lower amperage versions of these boards, to balance the charging of lithium batteries, as used in hand power drills...  

Well actually gave my friend a similar BMS from aliexpress which had good reviews, but he said that he put a better BMS for me, I checked the wiring and it seems like everything is correct.

So you think I should let my battery continue charging so it will even out all the cells?...

Edited June 21, 2020 by msacco

[Dr_Ju_ju]

Are all the batteries exactly the same ?  as even in-brand differences may well show up as different charge rates etc.... 

[msacco]

1 hour ago, Dr_Ju_ju said:

Are all the batteries exactly the same ?  as even in-brand differences may well show up as different charge rates etc.... 

All the batteries are the same(Panasonic NCR18650B), brand new, tested to be the exact same capacity(3400-3500 mah), before installing all of them were discharged to 3.7V.

Edited June 21, 2020 by msacco