Other Parts Discussed in Thread: BQSTUDIO
Tool/software:
Dear Community Members,
I am using your BQ35100 fuel gauge to gauge the primary EVE ER34615 Li-SOCl2 batteries, and I have encountered essentially the same problem as mentioned in the thread I am following up on. The SOH value that I am reading does not correspond to the actual state of the battery.
According to the datasheet and the technical reference manual, I have successfully performed the initial calibration of the gauge using BQStudio, programmed the appropriate chemistry (CHEM ID 0664), set the EOS mode ("Operation Config A" register to 0x12), and the "Alert Config" register to 0x0b. Additionally, in the "Gas Gauging" tab, I set the values corresponding to the datasheet of the battery I am using ("Cell Design Capacity mAh" to 19000, "Cell Design Voltage" to 3600, "Series Cell Count" to 1, and "Max Load" to 300).
From BQStudio, I then moved to an external MCU, through which I conducted a series of test measurements. I used the cycle mentioned in the datasheet. During the first measurement cycle, I sent the NEW_BATTERY command before the GAUGE_START command and waited for INITCOMP. My subsequent measurement cycles were as follows:
- Setting the GE pin to high,
- waiting for INITCOMP and then reading the "Battery Alert" register,
- sending the GAUGE_START command,
- applying the load,
- removing the load,
- sending the GAUGE_STOP command,
- waiting for G_DONE and then reading the "Battery Alert" register,
- reading the registers with "Measured Z", "Scaled R", SOH, and checking the EOS flag,
- setting the GE pin to low,
- waiting for the battery to relax,
- repeating the cycle, going to step 1.
The load profile between steps 3 and 6 is as follows:
- 1 second of idle load around 10 mA,
- 100 ms load pulse of 300 mA,
- 1 second of idle load around 10 mA.
After sending the NEW_BATTERY command, the SOH value was 100%. With each subsequent measurement cycle, it then linearly decreased by 2% down to 0%, which certainly does not reflect the actual state of the battery. From the thread I am following up on, I learned that this 2% decrease corresponds to the value of "State of Health Max Delta". According to Onyx's response, I changed the value of "Cell Terminate Voltage" in the "Gas Gauging" tab to 900 and measured again. Unfortunately, this did not resolve my issue, and the problem persists.
Thank you in advance for your response.
Yours Faithfully,
Tobias Kveton
