Other Parts Discussed in Thread: BQ40Z50
Dear TI agent,
We have batteries (4S) running with the BQ40z50-R2 with external thermocouples. We are using all 4 TSX inputs for each cell.
However, some batteries have presented instabilities on some of the readings and normally all below the real temperature. For example, one battery shows TS1 at -5C while TS2 to TS4 at 25C (when at room temperature). The instability is such that sometimes the UT protection triggers and the battery cannot charge. Lifetimes also show that the delta temperature is in the range of 40C or higher for such batteries.
When opening the batteries to check if there is some issue with the thermocouples, the voltage comes back to the expected value (same as the other thermocouples). The cables look fine and they don't seem to have discontinuities or damages. Then, after a while it can happen again to the same sensor either during charging or discharging. These batteries don't seem to have a pattern correlated with their cycles. In addition, the connection between the BQ40z50 and thermocouples is through a connector and no passives in between.
I have some suspicions that my cause the issue:
1. The thermocouple cables are soldered to a cable that is then connected to the BMS PCB.
2. The battery is designed in an aluminum enclosure. Right after sliding the enclosure out the unstable reading gets back to normal but I cannot get it back to the error state when sliding it back.
Have you seen the issue before?
