BQ27426: Question about the Qmax update rule for Passedcharge*37%

Hello Dominik，

1、符合 Qmax 更新条件的 OCV 测量触发条件是什么？请帮助列出所有条件。

1、What are the triggers conditions for OCV measurements that qualify for Qmax updates? Please help to list them all.

Dominik Hartl11 said:

#1: It doesn't have to be continuous. The gauge must not take OCV measurements that qualify for Qmax updates in between.

2 只要燃油表保持下图中的放电状态，是否就可以不触发 OCV 测量？

2, Is it possible to not trigger the OCV measurement as long as the Fuelgauge is maintained in the Discharge state in the diagram below?

3、TRM中有两个参数Quit Current和Dsg Relax Time，是不是可以通过修改这两个参数(eg.Quit Current=2000,Dsg Relax Time=65535)，使Fuelgauge在进入Discharge状态后，即使放电电流低，也不会退出Discharge，从而不触发OCV测量？

3、There are two parameters Quit Current and Dsg Relax Time in TRM, isn't it possible to modify these two parameters (eg. Quit Current=2000,Dsg Relax Time=65535) so that Fuelgauge will not trigger OCV measurement after entering the Discharge state, even if the discharge current is low, the Fuelgauge will not exit Discharge, thus not triggering the OCV measurement?

4、修改Quit Current和Dsg Relax Time的值，是否有其它关联的寄存器需要同步修改？如何修改？

4、When modifying the values of Quit Current and Dsg Relax Time, are there any other associated registers that need to be modified simultaneously? How to do it?

5、修改Quit Current对Fuelgauge的测量过程和测量结果有什么影响？请帮忙详细罗列。

5、What is the effect of modifying the values of Quit Current on the measurement process and results of Fuelgauge?Please help with a detailed list.

6、修改Dsg Relax Time对Fuelgauge的测量过程和测量结果有什么影响？请帮忙详细罗列。

6、What is the effect of modifying the values of Dsg Relax Time on the measurement process and results of Fuelgauge?Please help with a detailed list.

#1: OCV must be outside the flat zone Qmax Invalid MaxV/MinV (depends on ChemID) and temperature must be inside the acceptable range Qmax MaxT/MinT (40 and 10 deg.C by default).

#2: The gauge won't attempt an OCV measurement if the state is discharge.

#3: This is theoretically possible but then you'll prevent DOD0 and Qmax updates for 18 hours and current must drop to below C/200

#4: There are no other registers. The process is the standard data memory update process as explained in slua801 www.ti.com/.../slua801 and the TRM.

#5: Quit Current controls entering relax state. The gauge performs the following main functions in relax:
* DOD0 updates based on OCV (this is the state of the cell. A true OCV (stable) is the golden reference for cell state (DOD). It's important for the gauge to measure this to cancel accumulated coulomb counter errors (which will eventually affect the accuracy of DOD).
* Qmax updates based on qualifying OCV measurements and qualifying passed charge.

If the gauge doesn't perform these measurements (e.g. Quit Current and Dsg Relax Time prevent this), then DOD can become inaccurate over time (this gets also updated for a full charge so it doesn't necessarily need relax). Qmax will not update. Once Qmax is grossly inaccurate, the gauge will measure non-sensical Ra values (this can also lead to the gauge stopping Ra measurements altogether) and capacity predictions (and as a result all gauging results) will become inaccurate.

#6: See #5.

Hello Dominik，

1、修改Dsg Relax Time的波及影响，理解如下：

仅延长了DOD的获取时间和Qmax的更新时间。对电量计的算法无影响，在满足Qmax和RA更新规则的前提下，对电量计预测的FCC也没有影响。

上述理解是否正确？

1. Modify the ripple effect of Dsg Relax Time with the following understanding:
Only the acquisition time of DOD and the update time of Qmax are prolonged. There is no impact on Fuelgauge's algorithm, and no impact on the FCC predicted by Fuelgauge, provided that the Qmax and RA update rules are satisfied.
Is the above understanding correct?

Dominik Hartl11 said:

#5: Quit Current controls entering relax state. The gauge performs the following main functions in relax:
* DOD0 updates based on OCV (this is the state of the cell. A true OCV (stable) is the golden reference for cell state (DOD). It's important for the gauge to measure this to cancel accumulated coulomb counter errors (which will eventually affect the accuracy of DOD).
* Qmax updates based on qualifying OCV measurements and qualifying passed charge.

If the gauge doesn't perform these measurements (e.g. Quit Current and Dsg Relax Time prevent this), then DOD can become inaccurate over time (this gets also updated for a full charge so it doesn't necessarily need relax). Qmax will not update. Once Qmax is grossly inaccurate, the gauge will measure non-sensical Ra values (this can also lead to the gauge stopping Ra measurements altogether) and capacity predictions (and as a result all gauging results) will become inaccurate.

2、在放电状态期间，

当放电电流<Quit Current时，Dsg Relax Time开始计数。

当放电电流>Quit Current时，Dsg Relax Time清零。

当放电电流再次<Quit current时，Dsg Relax Time重新从0计数。

上述理解是否正确？

2. During the discharge state, the
When the discharge current < Quit Current, Dsg Relax Time starts counting.
When the discharge current > Quit Current, Dsg Relax Time is cleared to zero.
When the discharge current < Quit current again, Dsg Relax Time counts from 0 again.
Is the above understanding correct?