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BQ20Z65-R1: Various questions on configuration settings

Part Number: BQ20Z65-R1

1.How does one completely reset the BMS (to wipe all state data)? We are experiencing bad learns and re-running the process does not always yield expected results. Is there any reason why we should not reset the BMS before initiating a new learn?

2. Under what conditions will the BMS reduce ASOC below the designed capacity of the battery pack?

3. Should we use impedance track in our application? Our load is constant – never changing. The only change in current draw will be from the BMS itself when load is not being applied. The load is also very small. Are we deriving a benefit from impedance track, or are we better off with a standard fixed discharge curve?  Our current continous load is 3mA and our current zero load continuous is 1.2mA with a Deadband setting of 3mA.

4. How does the BMS account for its own current draw? Is this a fixed value? Or is it measured? What is a typical value we should expect?

5. How does the BMS account for internal losses within the cells? What is a typical value we should expect?

6.  With an update status of 06 indicating impedance track is enabled, would we expect a difference in performance with an update status of 0E?

  • Hi Ashley,

    1. Reprogram your device with fw or import the default gg file.

    2. ASOC is RM/Design capacity. FCC can drop because of temperature and load or even aging.

    3. No, impedance track requires at least a C/10 current to work. You probably just need coulomb counting.

    4. The nominal draw of the gauge in normal mode is about 100uA, in sleep it's 40uA and in shutdown it's even less. We take periodic OCV readings to update capacity regularly

    5. We take periodic OCV. This will update capacity accurately

    6. 6 implies that you have completed one Qmax and Ra update cycle. 0E implies you have completed two cycle and the Ra tables have been optimized.