BQ27621-G1: Stronge SOC behavior

Alexis COGREL

Part Number: BQ27621-G1
Other Parts Discussed in Thread: BQSTUDIO

Hello TI team,

We are using BQ27621 fuel gauge in our product to monitor battery level. I developed driver folowing your recommandation. I configure : Design Capacity, Design Energy, Terminate Voltage and Taper Rate according to our Battery Li-on (3.7V, 2.6Ah, 9.62Wh).

To check the behavior of BQ27621, I do an application to evaluate the SOC returned by BQ27621. My application do always the same. Please see SOC curves result below:

I observe a very stronge behavior of SOC. I observe that at the end of battery level (around 10%) take very long time. SOC stay at low level (less 10%) around 40% of the total of battery life instead my application always do the same. Even if the 0% is well notified according to my configuration, to my view behavior is not correct. I can't accept to stay a very long time at a low SOC.

Can you please help me to understand what did I do wrong?

Regards,

Alexis

over 3 years ago

0 Nick Brylski over 3 years ago

TI__Mastermind 19195 points

Hi Alexis,

Are you able attach the .gg and logs from bqstudio?

Thanks,

0 Alexis COGREL over 3 years ago in reply to Nick Brylski

Prodigy 150 points

Hello Nick,

I am not use BQstudio. We configure BQ27621 directly by i2c with our uC present in our product.

Regards,

Alexis

0 Yevgen Barsukov over 3 years ago in reply to Alexis COGREL

TI__Intellectual 1080 points

One possibility is that your chemistry is quite different from default, for example you have NMC or NCA chemistry, while default is LCO.
This could cause up to 40% SOC error, and result in a behavior similar to the one you observe.

I would recomend to run a selection test for your chemistry using chemistry selection tool below.

In addition to showing best chemical ID, it also shows if your cell is suitable to be used for our different ROM-based devices, and if it has several chemistry selections, you can chose the one that is most suitable.