BQ27426: BQ27426

Hi Aldrina,

For clarification, after completing the golden learning with a 530mAh cell, a 410mAh cell has been attached to the gauge?

If so, this is most likely the issue. Changing the cell after golden learning has been done on a different cell will greatly effect the performance of the gauge since the values and measurements taken are for a different cell.

If you are using the 410mAh cell, we would recommend completing another learning cycle with that cell attached.

Regards,

Anthony Baldino

Hi Anthony

Thanks for the reply and suggestion I will check that. I wanted to confirm , what else needs to configured other that the golden learning parameters and configuring the chemID to get accurate values. As of my knowledge the BQ27426 is a ROM based gauge and we can configure only three custom chemID's right? Are there any more configurations to be done to get accurate values?

Thanks in advance

Hi Aldrina,

Yes, for bq27426 there are only 3 configurable chemIDs that can be used. We would recommend using the GPCCHEM tool to find the best fit.

Before learning, the most important parameters to configure are the golden learning parameters such as Design Capacity, Term Voltage, etc. After the learning cycle is done, it is much easier to tweak the other parameters to fit the application as seen fit. If there are accuracy errors that occur after the learning cycle, please let us know and we can work through them.

Regards,

Anthony Baldino

Hi Anthony,

Actually I received a chem ID value of 7459 , that has to be configured to the fuel gauge. They got the chem ID after analysis. Could you please help me if its even possible to change the value to 7459 ?

Thanks for your prompt response

Hi Aldrina,

For a chemID outside of the three preprogrammed profiles to be used, one of our flash devices would need to be used. This would not be possible for the bq27426.

If you send over the report from the GPCCHEM tool, I can take a look into it.

Regards,

Anthony Baldino

Hi Anthony,

I configured the golden learning data and also tried to update to a custom chemID. But still the voltage readings that I am getting from the fuel gauge is not quite accurate. I have put the device on charging mode. There is clearly a big offset in the voltage value. What could be the reason.

And how can I validate all the values that I read from the fuel gauge?

thanks

Hi Aldrina,

Was the chemID changed after golden learning has been done? This should not be done since it will greatly affect the gauging accuracy.

Regarding the voltage difference, has there been any calibration completed yet?

Regards,

Anthony Baldino

Hi Anthony,

I have configured the correct chemID, but I havent done any calibration yet for difference in voltage.

Thanks

Aldrina

Hello,

Today's a holiday and no one is in the office. We will get back to you tomorrow.

Regards,

Nick Richards

Hi Aldrina,

For clarification, when you say that the correct chemID has been configured, do you mean one of the three preprogrammed chemIDs for bq27426?

Can you please tell me how large is the seen offset for the voltage?

Regards,

Anthony Baldino

Hi Anthony,

I configured one of the preprogrammed chemIDs. when the USB is plugged in for charging the voltage rises by almost 2-3Volts, than when it is unplugged.

Thanks

Hi Aldrina,

Are there connections on the schematic between the cell and USB that could cause this rise in voltage?

If you send the schematic we can take a look into it.

Regards,

Anthony Baldino