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pdove had a similar incident which prompted the troubleshooting and repair of the TCCH/Elcon charger thread.

Did your pack ever get overdischarged down to a very low level, or hit any sort of low voltage limit?

i consider Full voltage as 3.33 volts per cell for that chemistry--and feel that there is no benefit to charge higher.

It sounds like your charger is set to charge to 156 for the pack, but the CV stage cutoff current limit was never reached to turn it off. This could happen in a pack with one damaged cell, and if held long enough will damage other cells, such as you have experienced.

You may be able to use the tiny push button on the control board to adjust for lower voltage, depends upon what table was used to program the button settings, and if this is listed on the charger label or tag.
 

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You may want to survey your pack by using a voltmeter to check each individual cell voltage and see how closely balanced they may be. Keep a log of this over time and you may see a trend. If one or more gets out of line with the others, then that can aggravate the UV alarms and OV charging situation.
 

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Re: BMS Problem

i would guess that the BMS is seeing a low pack voltage and sounding/setting the Under-Voltage alarm signal.

you could test this by putting a voltmeter across the pack and watch what happens to the voltage when you accelerate down into the 200 Amp region. Depending upon the age and condition of the cells, etc. it may be dropping 50 volts or more from the at-rest voltage, and this may be below the BMS setpoint.
 

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If the sample rate of the digital fuel gauge is too slow, then you may not see the under-voltage during acceleration.

How are you measuring current--Is it the same digital gauge? What is the update or sample rate?
 

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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
 

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