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Sounds like a BMS problem to me. I never used a Mini-BMS but if you draw a picture of the way it is wired we might be able to solve this. You BMS should shut off the charger if a high voltage event is detected. It is definitely not a charger problem.
 

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The manual says that the high voltage cut off may or may not turn off your charger depending on the setting you use. HVC is selected at time of purchase..... so you need to find the value for yours.

You have 45 cells which can charge up to 3.65 volts per cell with a normal Elcon charger which would be 164.25 volts. You claim it reads 156V but that is only 3.47 volts per cell so that tells me that the charger if off at that point but hard to tell bu what you have said.... usually a CALB cell will read 3.38 volts after the charger shuts down and it has time to settle.

What voltage is your charger set to terminate and what HVC is your BMS set to? You appear to have a disconnect here.
 

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What Kennybobby said may be true but if I am not mistaken the BMS is looking at individual cell voltage so a single cell can cause the alarm which you may not see in the pack voltage. Can you set up a camera to watch the leds and see which cell is the culprit or do the leds latch on. I never used one of these Mini BMS before. Maybe have someone else watch the less while you drive if that is possible
 

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My guess was you had it wired wrong and it wasn’t turning off the charger so you overcharged them multiple times. They could all be damaged which will appear as lower capacity. If you have a way to discharge them one at a time and then charge them one at a time and measure the amp hours in and out you could determine if any were damaged. Personally I think battery balances shorten the life of your cells anyway. I don’t know of a simple solution to your problem.
 

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As I said you need to characterize your pack to know what you have before you can proceed with confidence. A lot of work I know. The issue with replacing new cells with old cells is that the voltage will drop faster on old cells because of capacity fade leading to unbalances in the pack. If you have the BMS set up to balance the cells at the top then that's probably as good as it gets. The low voltage alarm should keep you from loosing more cells depending on the voltage it uses to trigger. If you have a high voltage and low voltage alarm i don't see how you would continue to loose cells.
 

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+1 on what paul said.

if you ever over-discharged the cells (took them too low), then the damage was done. Some may take longer to manifest than others, but they have been bit and will die.

From what i have seen and read about that chemistry i wouldn't want to charge above 3.34 nor discharge below 3.0--there is no real energy available outside that band, and the risk of damage is too high.

just my 2¢, ymmv
Not exactly the same thing Kenny..... That is a discharge curve you need to analyze a charge curve. It has been a while since I looked at this but to my recollection when charging you charge at CC until that voltage is reached and then CV or hold the voltage till some current cutoff. It's really the CV mode that one can avoid and voltage is not really an issue. You can calculate the energy under the curve and see that it's maybe 5% of the total you put in the cell. I charged mine to 3.65V and then cutoff the charger skipping the CV mode altogether. There are several papers out where they experimented with different voltages .... i might still have them if you want to read them. Also, in my own experiments that during the CV mode the temperature in the cell rises dramatically in a short period. If memory serves it was a 50% temp rise in 5 minutes up to 50 C or something before I shut it down.
 
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