Yeah that’s probably the BMS protection triggering. I’d check all the balance wires to make sure they’re in order and have a good connection. Also check that the B- wire is correctly connected to the pack negative. If that’s all good the BMS might be bad or got damaged if you were building the pack with the connector plugged in.
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I always build packs with the BMS completely disconnected.
DMM to the rescue, I extended a balance wire and didn’t check continuity. Fixed it now.
Now to figure out the last twoish groups, checked them with the DMM and balance leads look Gucci
I feel like discharging to 20% and back up to 80-90% should fix this
Check the actual voltage of group #11 with a multimeter, at the cells preferably. #12 is fine
It’s pretty damn close to what the BMS is reading
If those are brand new cells then something is definitely wrong. You don’t just balance that sort of imbalance out on the first cycle. I’d take that group out and either replace the whole thing or test each cell individually and replace the bad one.
They’re not brand new but they’re not used either, they’ve been sitting in my garage for a couple months.
At what voltage were they sitting?
I left them all at 4.2V
The 4 that went into this p-group all tested the same going in, about 4.0-something volts.
Next time let them sit at 3.5 - 3.6V
Now I know,
Knowing is like 90% of the battle
So do you think I need to make a new p-group or should I just charge this one? Or cycle the pack?
Did you measure the P groups with a multimeter and compare it to what the BMS reads?
Yup and it’s basically the same ±0.005v
Charge that one group up to match the rest
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Charged my 12s10p pack up and it ended like this… Pretty sure the BMS should have stopped group 2 rising up above the rest! Not sure if the BMS is playing up. Don’t like the 0.1 V difference
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I’m having the same issue but only 1 group is low and the rest are high for me. The best advice I’ve had so far is to completely disassemble the battery, remove the affected group and charge or discharge it “manually” until it matches the rest.
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that’s not how xiaoxiang works. It cannot “stop” just one or two groups from rising while waiting for the rest of the group to catch up. Once one of the group reaches the set value for max voltage it stops the charging of the entire pack… just like any other bms. Well, it can technically “stop” just one or two groups from rising for the rest of the group to catch up but to do so you have to be charging the pack with current less than or equal to the balance current of the bms which is roughly just about 0.05Amps.
me either
should be easy to deal with admin version of xiaoxiang app
parameter view not param settings
Set desired balance voltage and max voltage diff among groups.
I’ve set mine to 4.045V.
Any group with voltage higher than that will be slowly discharged until they reach down to the set value.
Any group with voltage lower than that would be left untouched.
eg. if one group is at 3.991V and the rest are greater than or equal to 4.045V, then that one group would remain 3.991V while the rest of the group will all be discharged down to roughly 4.045V after several days of sitting idle.
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Surely if it’s just stopping the pack once one group reaches charge then it’s not balancing anything?
To be honest, if I had a difference like that on a new pack I would be quite concerned about that group 2.
It could be indicative of a bad cell in the group, or bad welds.
Were the cells reasonably well balanced when you started the charge?
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