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BQ78350-R1: DOD at EDV2

Kazuki Itoh
Genius 10730 points
Part Number: BQ78350-R1
Other Parts Discussed in Thread: GPCCEDV

Hello team,

My customer observed that DOD at EDV2 gets smaller after reaching the first EDV2.

1. Could you please tell me how DOD at EDV2 is calculated?

2. Could you please tell me how to fix DOD at EDV2? Is there any configuration which allows to do that?

Regards,

Itoh

  • 0
    TI__Guru* 81034 points

    Hi Itoh-san,

    DOD at EDV2 is updated along with FCC after a qualified discharge. This is a parameter in data flash and according to the TRM should be initialized to (1 - Battery Low % / 100)) x 16384. If they make any change to Battery Low % in their data flash settings, this value needs to be updated as well. 

    Here is an example of how DOD at EDV2 works. The device tracks DOD (depth of discharge is a code between 0 and 16384) internally:

    Suppose FCC is 1000 mAh and Battery Low % is 7% and DOD at EDV2 is 15232

    capacity from 100% SOC to EDV2 would be 15232x1000/16384 = 930

    capacity from EDV2 to 0% SOC would be 1000 x 7/100 = 70

    the sum of these two numbers (70 + 930) is 1000

    After a qualified discharge, the device records the DOD at which EDV2 was detected and calculates the new FCC.

    If there is false EDV2 detection due to poor setting of the CEDV parameters or due to a pulsed load, it may result in bad values for the new calculated DOD at EDV2 and Learned FCC. Make sure they have used the GPCCEDV tool to calculate the CEDV parameters. If they have high pulse loads, they should use the Overload Current parameter,  set VFLT_EN, and possibly extend the EDV Hold Time parameters to avoid false detection.

    Best regards,

    Matt