What makes a cell group just die?
- Thread starter eikido
- Start date
Could have been a weak cell in the pack that took that parallel group down.
^-- a major cause of this could be that the battery was fully discharged and left idle for a long time.
Could have been that the BMS draws all it's power from that 1 cell, and wore that parallel group down over time.
Hard to tell after the fact!
Was the failure gradual or sudden?
^-- a major cause of this could be that the battery was fully discharged and left idle for a long time.
Could have been that the BMS draws all it's power from that 1 cell, and wore that parallel group down over time.
Hard to tell after the fact!
Was the failure gradual or sudden?
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If it's a BMS issue it will take out the same group again.
If you have access to the balancing resistors (assuming a balancing BMS, and assuming it's resistive shunting type), then when you connect up the new cells to it, and you know that the new cells are below the balancing voltage, connect a multimeter set to 20VDC or less with one probe on each end of that cell group's balancing resistor (often a black rectangle with silver ends marked 101 or similar, in a row of identical parts, one for each cell group).
Any balancer taht is on will have a voltage across it generated by the current thru it. Any balancer that is off will not.
If you have access to the balancing resistors (assuming a balancing BMS, and assuming it's resistive shunting type), then when you connect up the new cells to it, and you know that the new cells are below the balancing voltage, connect a multimeter set to 20VDC or less with one probe on each end of that cell group's balancing resistor (often a black rectangle with silver ends marked 101 or similar, in a row of identical parts, one for each cell group).
Any balancer taht is on will have a voltage across it generated by the current thru it. Any balancer that is off will not.
Many thanks for the response.
I do not know if it was gradual.
But the other cells were indeed fully charged and the battery was sitting unused for about 3 months.
Why can a fully charged battery, sitting idle, have a cell group killed?
I will not take the risk and change the BMS.
I do not know if it was gradual.
But the other cells were indeed fully charged and the battery was sitting unused for about 3 months.
Why can a fully charged battery, sitting idle, have a cell group killed?
I will not take the risk and change the BMS.
eMark
100 kW
Could be a either a BMS defect, battery fabrication defect or cell defect in that parallel group as previously suggested.
As far as you know were the cells name brand A-grade cells OR no name Chinese cells? Figure that an A-grade quality fabricated 14s6p battery would cost at the very least $500 vs a $300 no name Chinese 14s6p battery of lesser quality.
For high performance cycle life it's always better to buy an apt Grin or EM3ev instead of a less expensive UPP battery.
We just answered that, see previous posts in this thread.
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