BQ34Z100-G1: Stops taking OCV measurements after a time

Part Number: BQ34Z100-G1 Hi, We have succesfully gone through a learning cycle and Update Status is 0x6. A few cycles after the learning cycle was complete, OCV readings stopped being taken and QMAX & DOD values stopped updating, with their respective counters just increasing above 100hrs even though we cycled the cells multiple times. My assumptions is that OCV readings should occur every time the fuel gauge enters relax? Interestingly when we reset the fuel guage and then do a few cycles OCV readings do occur for the first few times. Then they stop again. Why would this be happening? Is it normal behaviour? Will the fuel gauge decide to take readings after 200hrs or somthing? Thanks James

Hello James, Can you show me the test using a bqStudio log file?

Hi, It is very difficult as the fuel gauge is floating at high volts. I can give you all the register values if that helps? But I think it easiest first to answer my initial question, should the fuel gauge take OCV measurement and update DOD/QMax on every cycle? Or does it only do it every 10 cycles or something?. Thanks, James

Hello James, OCV measurements are taken when the stack voltage reaches a dv/dt condition of < 1 uV/s. It does not do it via cycle count.

Hi Kang, Ok, thanks. Any ideas why it would take a few OCV readings after a reset and then never take any more? Would it be helpful to do a charge to 100% then turn off the charger and begin the bqstudio log file? All it will show is no OCV measurement is ever taken. Or would you like the register values? We have a second unit programmed with the golden file from the 1st unit and it does the same thing. Thanks James

Hello James, It depends on how stable the voltage is and whether or not IT is enabled. Yes, I think you should log a bqStudio file for us. I would like to look at the voltage and a few other debug registers such as DOD0. bqStudio logs all these by default.

Hi Kang, I have attached the log file. I started it a few minutes after full charge was reached. It ran overnight and no DOD0 or Qmax updates were seen. Our system is 16 x 100Ah 3.2V LIFEPO4 cells in series I notice that the voltage fluctuates by one ADC sample which equals 16mV for our system (16 cells in series). This can't be the issue can it? Cheers James

log after charge 4-14-20.zip

Hi Kang, Do you need me to collect any more information? We are almost ready to release our product and this is holding us up. We would really appreciate some help Thanks James

Hello James, Thank you for the log files. Can you send me the bqz file you are using in bqStudio? The default directory is C:\ti\BatteryManagementStudio\config\ We may need to open up a parameter for you to modify. If it is the default bqz, just let me know.

2728.0100_0_16-bq34z100G1.zip