Temp outside was 107*, inside the shed was less than 120*, so I can not see that being the problem.
I had two days prior added "Heltec Whole Group Balancer " to the mix, but can not imagine that overriding the BMS to allow runaway voltage.
The BMS, from aliexpress, was only one week new replacing a Daly which allowed up to 3.7v -Daly stated was OK but I could not get comfortable with.
Also, I am more comfortable topping out at 3.4V/13.6v to extend life of cells (I thought...)
Cell 1 expanded almost uncontrolled. Currently sits at 3.3v SOC after 4 days.
Cells 2,3,4 expanded but much less so. They currently sit at 3.50/51V.
So, a couple of questions:
-I assume the BMS is the cuplrit -any thoughts? I certainly do not want to attach it to my good bank to experiment.
-Is it possible that it was simply a faulty cell? I have had them for just over 1 month, but have certainly less than 10 full cycles of use.
-How could I test the remaining 3 to verify fitness for service, without pulling another cell from my good bank?
-Or is this simply an horrible idea, and just walk away from the $525 worth of cells?
I purchased cells from an amazon seller with no feedback, suspect, but do not want to pursue chargeback without a high degree of certainty.
Thank you in advance for any assistanceView attachment 55938View attachment 55939
That is a JBD BMS, what are the settings? Any alerts (like over voltage)?
Certainly if not connected correctly, an active balancer can cause problems.
Do you have a close up picture of the active balancer? I ask because there are different settings for it fo different chemistry cells.
Did you need the active balancer, or just decide to add it?
Perhaps screen shots of the BMS settings, and a close up of the active balancer can assist with diagnosing the problem.
My cells in the garage in Arizona regularly hit high temperatures, however I try to avoid charge and discharge when too high, a swamp cooler can help cool things off by up to 20 degrees if you have low humidity.
One of the reviews on Amazon even shows what I'm talking about for the active balancer: