What current was passing when you measured the voltages?
What is the maximum current the BMS can handle?
What size and length of wires are you using?
Side issue, but worth stating, if you are using a BMS, you should almost certainly be top balancing not bottom balancing.I had an issue when I did the bottom balance test.
Adding to this, even if you think bottom balance makes sense for your context, if you bottom balance but use a top balancing BMS, your manual balance and your BMS are working against eachother (the BMS will immediately set to work trying its hardest to undo what the manual balance did) at least that is my understanding.Bottom balance is for EV type use where the battery is taken down to low SOC. For house battery use it is better to top balance.