BQ27621-G1: Battery compatibility

Sepeedah Zadeh

Part Number: BQ27621-G1

Team,

Can BQ27621-G1 be used if the cell chemistry is LiCoO2 and the maximum voltage is 4.2V, but we only charge it to 4.1V? from the related thread I see, seems like the answer is no, but wanted to verify before telling the customer

Best, Sepeedah

over 2 years ago

0 Jackson DiGiovanna over 2 years ago

TI__Expert 8245 points

Hi Sepeedah,

I don't see any reason why this chemistry would not work with this gauge. You can use the GPC Chem tool here https://www.ti.com/tool/GPCCHEM to find the closest ChemID match to your particular cell. Can you point me to the thread you are referring to so I can take a look though?

Thanks,

Jackson

0 Sepeedah Zadeh over 2 years ago in reply to Jackson DiGiovanna

TI__Intellectual 2850 points

Hi Jackson,

I was referring to this thread (also shown at the top of this thread): https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/973271/bq27621-g1-suitability-for-a-4-1-v-single-cell-battery

So although battery is spec'd at 4.2V but charging up to 4.1V will mess up the SOC reading sounds like? I'm not sure, so that's why I was asking. This gauge only support three profiles with 4.2, 4.3 and 4.35V as I understand. There is no option to program other profiles to this gauge.

+1 Jackson DiGiovanna over 2 years ago in reply to Sepeedah Zadeh

TI__Expert 8245 points

Sepeedah,

Oops, sorry I didn't see the linked thread at the top.

If you select the 4.2V CHEM_ID here and only charge to 4.1V there should be no issue as you will still always be getting valid readings from that chemistry's OCV curve. The only issue would come if you charged over the maximum voltage (ex: charging to 4.4V with 4.2V programmed in).

Thanks,

Jackson

0 Sepeedah Zadeh over 2 years ago in reply to Jackson DiGiovanna

TI__Intellectual 2850 points

No worries, and thanks for the feedback Jackson! Ok, the other thread was a little confusing, since it was the same question, but the answer was a hard no :)

+1 Jackson DiGiovanna over 2 years ago in reply to Sepeedah Zadeh

TI__Expert 8245 points

I will say that what Nick said about the bq27421 being a better option here isn't necessarily incorrect either. The bq27621 uses voltage correlation and interprets current values rather than physically using a sense resistor like on the bq27421. So while the bq27621 is compatible, I would expect better accuracy from the bq27421.

0 Sepeedah Zadeh over 2 years ago in reply to Jackson DiGiovanna

TI__Intellectual 2850 points

Thanks Nick, makes sense!

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BQ27621-G1: Battery compatibility