It’s had barely any use tbh. Will put it on facebook then
No, like there’s barely any risk in using it lightly. If it balances out, which it likely will, you can use it like normal.
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What could be causing the unbalance? - someone suggested it was the nickle connectors on that series (11) and that i may need re-attaching. Could it be anything else?
Well, it’s not likely to come right back into balance, is it? I would think until it’s fully balanced again you’d be at a big risk of accidentally over-discharging that group. You probably know more than me, but I would think this is the kind of thing where maybe you can get it back with a lot of balancing and it will be usable, but if you just start using it you could make things worse without really watching that group.
In my non-expert opinion, since it was sitting it was probably self-discharge. One or more of the cells in that group is likely self-discharging faster than the rest of the cells. If that is it then it isn’t catastrophically bad because in a year it’s not even really close to getting the group into the danger zone. If it was used regularly that might not even be noticeable.
That would be my guess though. The nickel connection breaking would mean you see an imbalance after use. If it’s just sitting there and all cells are self-discharging at the same rate it wouldn’t even matter if one of the cells disconnected as far as the BMS can tell until you went to use it.
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If it were me I would definitely be cautious about what voltage I drain the pack to, but after fully charging a few times, if there isn’t a bad cell or something it might come back. Could take a while to balance though
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that makes sense. Thanks for explaining 
Cells have passive drain. Some drain faster than others. It’s somewhat normal for a year old pack that’s been idle. Are these Samsung 30q
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No, they’re 40T
Yeah classic Samsung. It’ll probably balance out
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Reassuring man, I appreciate your help
Hey! Just to be sure, my p- wire (16awg) of my bms is too short. I will use it for my leds (bypassing) so I would like to extend it with some 22awg wire. Would this cause any problems?
No. Just make sure 22awg can carry enough current
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How many amps do your LED’s draw?
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Uhm there will be a buck inbetween with max output current of 3A. And I will make use of about 30leds so that would be about 1,8A.
If you decide to charge it to see how it balances out I recommend doing that very slowly. Either for the entire charge or once the pack reaches about 3.8V-3.9V/cell or so.
The slower the charge the greater the effect of the balancing.
I dont own a fast charger - i think it takes 3-4 hours for a full charge with the charger that I have. Do you think that is slow enough?
There’s no real threshold for fast/slow. The slower you go the better since that makes the balancing current a larger percentage of the total charging current and that allows for more balancing to be done before the pack is fully charged.
Charge with whatever you have and, if you can, set your BMS to balance when not charging. You might find it all balances out after a few of days of sitting after this charge or, depending on how the BMS wants to work, you might have to cycle the pack a few times in order to get it balanced.
Another option, to check the health of the pack, is to charge it fully and let the BMS try to balance the pack. Once the BMS seems to have stopped doing that then turn off balancing and leave the pack alone for two hours or so for the voltages to settle.
Then measure each cell voltage and then leave the pack alone for a week or longer. Then check each cell voltage again. If group 11 is a lot lower than the other groups then you either have one or more cells that are damaged, have reached the end of their life, or something is wrong with the pack or the BMS.
If all the p-groups look fairly close together in voltage after a week then your pack might be okay to use.
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Hey, you’re private so i cant dm but maybe i can help. Im in the pmw usa (Seattle specifically) and id be willing to take a look at it for you and get it balanced and run a few charge discharge cycles if youre interested. Im not fast, it’s just a hobby for me, but i have all the equipment.
I also collect used cells for a power wall and recycle packs for various uses but if im testing it for you i dont buy them, to conflicting interest for me. Either i buy it or i test it.
Imho that pack will probably come back into balance but idk without putting it on my bench
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$3.99/cell for Samsung 40T 21700! (33% off) Are there any other cells this affordable these days? How often do you see sales like these?