BQ27542EVM: SOH Load I setting question

Hi Anthony,

I have a question about the BQ27542 State of Health (SOH) calculation.

Does it take into consideration QMax*IR@25 degC?

Does it reference the RA TABLE for updates?

The Technical Reference Manual (TRM) explains that SOH = FCC/Design Capacity, but FCC is not displayed in the registers.

How can I confirm the accuracy of FCC and SOH?

Please help me confirm.

Thanks!

Regards,

Yan Yu,Tuan

Hello,

Below is how FCC is calculated within the algorithm, which can help you confirm the accuracy of the value. This can be found along with more information about the Impedance Track algorithm in the document attached:

Using this FCC value, you can confirm the SOH calculation by dividing it by the Design Capacity.

https://e2echina.ti.com/cfs-file/__key/telligent-evolution-components-attachments/00-24-00-00-00-00-02-91/Theory-and-Implementation-of-Impedance-Track-Battery-Fuel_2D00_Gauging-Algorithm.pdf 

Regarding the FCC calculated by the gauge, it should be able to be seen in the registers here:

It can also be found by reading registers 0x12 and 0x13:

Regards,

Anthony Baldino

Hi Anthony

The TRM describes the FCC value used is not necessarily be the same as FullChargeCapacity data.

Is there a possibility of a difference between these two values?

Regards,

Yan-Yu,Tuan

Hello,

Yes, there is a possibility in a difference in these values if the temperature of the cell is different than 25 degrees or if the load current of the application is greatly different than the set State of Health load current.

Regards,

Anthony Baldino