How to modify the source code of nPM PowerUP application to reduce the lower limit of battery capacity?

[Michael Chenb]

Hi, 

Our project has chosen nPM1300 as the PMIC, and our project's battery is only 28 mAh. When we tested the battery configuration file using the nPM PowerUP app, we found that the lower limit of the battery was 32 mAh.

We obtained the source code of the nPM PowerUP application from Git hub and found the lower limit setting in the code. We modified it to 26 mAh and built it locally. Afterwards, we connected it to EK for testing, and the modification seemed successful, and the software ran normally.

What I want to confirm with you is that if we want to change the battery capacity limit of the nPM PowerUP application, we only need to modify this position?

Thanks.

Michael Chenb

[Kazi Afroza Sultana]

Hello,

It may be a temporary solution but there would be compatibility issue. I have checked with our PMIC team and got the following feedback:

32 mAh lower limit in nPM PowerUP reflects constraints in the supported charging and profiling setup, including the nPM1300’s minimum charge-current setting of 32 mA and nPM FG board minimum discharge current limits. Changing the application limit may allows a smaller capacity to be entered, but does not change these hardware constraints, so modifying that field alone is not sufficient to confirm compatibility.

For a 28 mAh battery, we recommend the nPM1304 PMIC, which supports lower charging currents and other features suitable for such small-capacity batteries. The nPM1304-EK also integrates the functionality needed for battery profiling, without requiring a separate nPM Fuel Gauge board.

If you still need to retain the nPM1300, I would suggest you can leave the capacity setting at 32 mAh and perform the profiling. The profiling process determines the measured battery capacity and use that in the battery model for fuel gauging ( it does not simply use the entered 32 mAh as the final capacity).

But, first verify that your battery supports the configured charging configs with nPM1300. In particular, nPM13000 lowest ICHG limit, 32 mA is approximately 1.14C for a 28 mAh battery, which must be within the battery manufacturer’s charging specification and also the ITERM.

Thanks.

BR

Kazi

[Michael Chenb]

Thank you for your reply.

The profiling process will not simply use the input 32mAh as the final capacity，this information is very important for us, so we don't have to worry about whether I need to input the 28mAh as the battery capacity.

Another issue we are concerned about is that as the use time increases, the battery capacity will further decrease. For example, if the battery capacity drops to 60% of the initial capacity after two years, will our fuel gauge or battery profile track this capacity decrease?

Thank you for your professional support!

Michael

[Kazi Afroza Sultana]

Hello,

'' if the battery capacity drops to 60% of the initial capacity after two years, will our fuel gauge or battery profile track this capacity decrease?''

Yes.

See this link: https://docs.nordicsemi.com/r/bundle/nan_045/page/app/nan_045/soh.html 

[Michael Chenb]

Thanks so much.

[Kazi Afroza Sultana]

You are welcome.