BQ40Z50-R2: QMAX update is not working with OCVFR bit set

David Zander

Part Number: BQ40Z50-R2

Hello everyone,
I am using the bq40z50-R2 for a 3S1P battery. Afterwards I performed a successful learning cycle I reduced the charge voltage in the golden image to 4.1V per cell because this is given by the application. Now the QMAX update does not work anymore and the OCVFR bit remains set if the battery is fully charged.
Is it possible that I am still in the flat region with a charge voltage of 4.1V per cell? I use the Chem ID 0x2481. Is there a workaround if the flat region is really that big?

best regards
David

over 5 years ago

0 Andy Liu (BMS) over 5 years ago

TI__Guru 52115 points

Hi David,

Which Qmax update are you talking about? 37% passed charge of DOD is required for the 2nd and subsequent Qmax updates.

Do you mean these Qmax updates?

Andy

0 David Zander over 5 years ago in reply to Andy Liu (BMS)

Prodigy 20 points

Hi Andy,

yes, exactly. I have understood that the OCVFR bit has to clear during charging for a QMAX update (Technical Reference Manual SLUUBK0B: 6.4.2 QMax Update Conditions). Is that not the case?

best regards
David

0 Andy Liu (BMS) over 5 years ago in reply to David Zander

TI__Guru 52115 points

Hi David,

I have checked the flat region for your chemistry id #2481. Its actually from 4043mV to 4078mV. An OCV reading will not be taken if the voltage is inside this range.

Andy

Power management

Power management forum

BQ40Z50-R2: QMAX update is not working with OCVFR bit set