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BQ40Z80: Changing Battery Pack usage range to 80%

kimS
Prodigy 190 points
Part Number: BQ40Z80

Hi Expert.

I  would like to apply a new function that allows the user to limit the charging amount while using the battery pack.

Which concept is user select the DOD 80% or 100% (Depth Of Discharge)  for battery safety and SOH.

I have plan to change the following registers via 0x44 write command,

I'm worried about SOC accuracy because there is no running cycle.

Is there anything worth mentioning?

1. FD : Set Voltage Thd. Clear Voltage Thd

2. TD : Set Voltage Thd. Clear Voltage Thd

3. Term Min Cell V

4. Design Capacity (mAh) , Design Capacity (cWh)

5. FC : Set Voltage Thd. Clear Voltage Thd

6. TC : Set Voltage Thd. Clear Voltage Thd

7. Charge Voltage : all temp. range

8. Protection Thd.

  • 0
    TI__Mastermind 28470 points

    Hello,

    Regarding changing the capacity values to reach either a 100% or 80% SOC for charging, we do not recommend doing this because changing back and forth from these two different values can affect the gauging algorithm and make it incorrect.

    You can change the voltage level that the battery charges to for full capacity, however we would not recommend changing the values that directly affect the gauging algorithm.

    Regards,

    Anthony Baldino

  • +1 in reply to Anthony
    Prodigy 190 points

    Hi Anthony Baldino

    Thank you for your reply. I understand there is such a risk.

    I am curious about how products like smartphones implement this functions

    which reduces the charging voltage to 80% and implements SOC from 0 to 100% accordingly.

  • 0 in reply to kimS
    TI__Mastermind 28470 points

    Hello,

    Understood, I believe looking into the bq40z80 Valid Charge Termination would be beneficial.

    Changing the conditions of the Valid Charge Termination could allow for the cell to stop charging at a lower voltage (80%) while still allowing the SOC to be read from 0% to 100% accordingly.

    More information about Valid Charge Termination can be found in Section 5.6 of the bq40z80 Technical Reference Manual below:

    https://www.ti.com/lit/pdf/sluubt5 

    Regards,

    Anthony Baldino