I have an older 2 kw battery. Recently I noticed that it is badly out of balance (by more than 0.2 v). But actually it is all 8 of the last battery strings that are like 3.73 v, while the first 16 are 3.95 v.
Has anyone seen this? Is my battery misconfigured? (See screenshots)
My current plan is to discharge it a bit (down to about 88 v or so), take it apart and carefully balance the last 8 strings manually.
@Pdwhite – Thanks for marking this as support. You’re definitely the person who would know the most about this. But just in case it was unintentional: because this is marked as a private message I don’t think its visible to other people. Part of my question is whether anyone has seen a whole set of strings go out of balance – I’m not sure how that might have happened!
I have opened the battery at this point, and confirmed that everything plugged into the small connector (board 2) does indeed have a lower voltage. So its not just something miscalibrated in the BMS (though it could still be an issue with the BMS that caused the imbalance!)
Sure, no problem. My guess right now is that it is the BMS , if it’s been sitting for a while (which I mean this is the older battery), is kind of drawn down on those strings in particular. What I would do is definitely charge up to full, let it balance charge out, so just leave it plugged into the charger while the balance is going until all those other cells match up.
I ended up doing a manual rebalance (charging at about 1.5 A across the block of low strings), and everything seems good so far. I wasn’t sure how long it would take the limited passive balancing to bring everything into line.
