Timing requirements nrf_fuel_gauge_process

[Bogdan Marinescu]

Hi, I am looking at the documentation of the fuel gauge API, specifically at "nrf_fuel_gauge_process" (https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrfxlib/nrf_fuel_gauge/doc/api.html#c.nrf_fuel_gauge_process). While the documentation states "Current and voltage measurements do not have to be made at a certain interval", I couldn't find anywhere some guidelines regarding the recommended timing of this function. Specifically, I'd like to know if there is a maximum period for calling nrf_fuel_guage_process that keeps the estimations reasonably accurate. The "nrf_fuel_gauge" sample runs the update function every second, but I'd like to knoe if it can be called (much) slower than this.
Thank you.

[helsing]

Hi Bogdan,

Just letting you know we have started looking into this. I will get back to you after the weekend.

Best regards,
Håkon

[helsing]

Hi Bogdan, sorry for the delay. Here is the feedback from our PMIC team:

The Fuel Gauge period is based on the device operating state or the activity levels.

For a typical active period in any BLE application at least once a second is a fair call since total charge is just 10µC for one iteration (this includes both sensing and processing). This is negligible overhead during higher activity levels.

During sleep there is no need to wake up just to run the fuel gauge algorithm.

I couldn't find anywhere some guidelines

Thank you for the feedback. Within in a few weeks time we will likely be updating some of the fuel gauge app documentation related to power consumption and timing.

[Bogdan Marinescu]

Thanks for your reply, but I don't thnk I understand it completely in the context of my question. In our application, BLE is not necessarily active all the time, so the BLE references are only partially helpful. So I will rephrase my question: I'd like to know if it's OK to wake up every 10 minutes or more, call "nrf_fuel_guage_process" and then go to sleep again for 10 minutes or more. I understand that this should be possible if I also call "nrf_fuel_gauge_idle_set" with a good "i_avg" estimation, but I wanted to make sure that this is OK.

[helsing]

Hi Bogdan, sorry for another delay. I am checking this up and will get back to you soon.

[helsing]

Bogdan Marinescu said:

I'd like to know if it's OK to wake up every 10 minutes or more, call "nrf_fuel_guage_process" and then go to sleep again for 10 minutes or more.

Yes, I can confirm this is OK. This is the way to go for ultra low power fuel gauging with nPM1300