BQ40Z50-R2：Ra Filter function

Hello Yan,

The function of the Ra filter "Filter value used in Ra Updates and specifies what percentage or Ra update is from the new value (100% setting) versus old value (setting). The recommended setting is 80% if the [RSOC_CONV] feature is enabled. Otherwise, the setting should be 50% as default.". The main function is essentially updating the Resistance table due to the internal impedance of a cell changing with age/use. Adjusting will affect the SOH reading due to the SOH taking the Ra table into account, however it is recommend to keep it out the default.

Technical Reference Manual:
https://www.ti.com/lit/ug/sluubk0b/sluubk0b.pdf?ts=1741624600141&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FBQ40Z50-R2


Thank you,
Alan 

Hi Alan,

Thank you for your response.

Why is the setting at 80%? Can you explain it?

What would be the impact of setting a higher value, such as 90% or 100%?
What would be the impact of setting a lower value, such as 50% or 70%?

Best Regards!

Hi Alan,

Where is the formula obtained from?
Where can I find RA new & RA old?
If I change the Ra filter to 99%, will the new RA update only by 1%?
Will 99% use the old RA? Is that correct?

Please help confirm

Thanks!

Best Regards~

Hello Yan,

This is the filter algorithm:
Ra = RaFilter * RaOld + (1000 - RaFilter) * RaNew

The Ra max delta(change) is the maximum change from the old value to the new value.

The Ra table has a direct impact on the FCC. The gauge uses the resistance along with the expected load from the load select to simulate when the voltage will hit the programmed terminate. If the Ra table is higher then the voltage sill hit terminate sooner and FCC will be less and vice verse for lower Ra table. Regardless we still recommend leaving the value at default.

Thank you,
Alan

Alan Frias said:

direct

Hi Alan,

Is RA NEW the value after the RA TABLE update?
Is RA OLD the value before the RA TABLE update?

Best Regards!

Hello Yan, 

Yes that assumption you made is right.

Thank you,
Alan

Hi Alan,

Since RA FILTER is related to RSOC_CONV,
If we change RA FILTER to 50% or 99%,
Do you think RSOC_CONV should be enabled?

Best Regards!

Hi Alan,

Hi Alan,

Hi Alan,

Please check with the attachment.

Thanks!

0809.gg.csv

Have a good day!

Hello Yan,

We have received your repones and are looking into the matter, we will get back to you after our investigation.

Thank you,
Alan

Hello Yan,

I recommended to enable the feature due to it being a default feature and we recommend features to be set at default.

Thank you,
Alan

Hello Yan,

Can you export a .log file during the event to see what other parameters are changing during this event. The most likely cause could using the wrong ChemID and if that is the case than rerun the GPCCHEM calculator and select a error difference of 3% and below. Another cause is that you are using the right ChemID but a aged cell causing the sudden drop of SOH, or using a really heavy load on the system. Lastly your issue could be that you are using the system in a cold environment and if that is the case you can run a GPCRB calculator. 

Changing the RA Filter will effect the RA table but the likely issue is that your are using aged cells with a new Ra Table however within a couple of charge and discharge cycles the Ra Tables should update to become stable with the aged cells.

GPCRB:
https://www.ti.com/tool/GPCRB

GPCCHEM: 
https://www.ti.com/tool/GPCCHEM

Thank you,
Alan