My 280 ah cells were almost totally charged?

[Electric Personality]

I measured 3.32 on almost every cell, paralleled them for a few hours, and after finding my power supply would not go that low, I wired them in series and hit them up at 20 amps for a half hour. 15 volts! Yikes, hooked up a landing light to suck them down for a couple minutes and now sitting below 14.5. But it sure didn't take much to get them over 3.65 a cell!

 

[Electric Personality]

Here is how it is now... Is that too much disparity between cells?

 

[Steve_S]

Ohh that's nothing to worry about, if it was 1.5V difference between cells that's an issue but anything less than 0.750V isn't anything to blink over.
BTW, your Battgo is set for LIPO not LFP, you should set that properly. Verify your BMS is for LiFePo4 LFP and set properly for the chemistry. As for the imbalance, passive balancing would level that out quite quickly

 

[Electric Personality]

Yeah, caught the LiPo thing last night. Now set to LiFe, and this morning all within .005 of each other. How would I verify that the BMS is for LiFe? That is what I ordered (3.6/ cell), but is there any way to actually check? I was definitely surprised it took so little energy to top off the cells to an overcharge state though!

 

[Steve_S]

Yeah, caught the LiPo thing last night. Now set to LiFe, and this morning all within .005 of each other. How would I verify that the BMS is for LiFe? That is what I ordered (3.6/ cell), but is there any way to actually check? I was definitely surprised it took so little energy to top off the cells to an overcharge state though!

Well, since you haven't said what type of BMS you have there, I can't tell you how to verify it. Some are factory set and specific while others can be configured and adjusted / customized. If you provide the Make Model & Part Number and whatever else would be handy for people to be able to help you.

 

[Electric Personality]

Well, since you haven't said what type of BMS you have there, I can't tell you how to verify it. Some are factory set and specific while others can be configured and adjusted / customized. If you provide the Make Model & Part Number and whatever else would be handy for people to be able to help you.

Sorry, that would help. It is a Daly 200 amp, Not a bluetooth (that I know of anyway!), just Daly. Ran a little over $100 shipped. I know I ordered the right one, but no way of knowing that it actually is.

 

[Airtime]

I measured 3.32 on almost every cell, paralleled them for a few hours, and after finding my power supply would not go that low, I wired them in series and hit them up at 20 amps for a half hour. 15 volts! Yikes, hooked up a landing light to suck them down for a couple minutes and now sitting below 14.5. But it sure didn't take much to get them over 3.65 a cell!

Mine were nearly full too, measured between 3.328V - 3.335V on my 8 cells, amount to top off was as low as 1Ah and highest 24Ah. You do need to watch them carefully when manually charging, once they get above 3.4V it goes pretty fast. I charge in series up to about that but keep an eye on each individual cell voltage, if no BMS connected. Then top them off in parallel.

I would measure individual cell voltages and then discharge a bit further. I wouldn't worry too much about a short excursion up to 15V unless you had a mismatched cell, one could have gone much higher than 3.75V if out of balance. Look at the highest voltage cell and see if any swelling.