BQ34Z100-G1: SOC calculation error

Hi,

Was the GPCHEM tool used to get a ChemID match?

Was a learning cycle completed?

Was the gauge calibrated?

What is the chemistry and battery configuration for this application?

Are the cells balanced?

Regards,

Evan

Evan, 

Was the GPCHEM tool used to get a ChemID match? ==> Not realised with this log (file not match with GPC instruction).

Was a learning cycle completed? ==> Yes, a GFI was realised (max error = 1% / Qmax updated / Learning Status = 06).

Was the gauge calibrated? ==> Yes. Voltage and current < 1% error.

What is the chemistry and battery configuration for this application? ==> We use ChemID 7349 for a 7s2p (2 packs of 7 cells in series, in parallel) configuration.

Are the cells balanced? ==> Yes. It's a recent battery

Hi,

A proper ChemID match needed to be obtained before you can expect to see any kind of accurate SOC.

Please share the data input into the GPCCHEM tool and the report received from the tool.

Regards,

Evan

Hi, 

Here the GPCCHEM report : 7s2p - ChemID7349-report.zip

As you can see, the ChemID 7349 choice is not bad (third choice).

Hi,

Assuming that the log file for the GPCCHEM tool is ok, 7349 is a good match.

I looked at your original log file sent, and I don't see where the battery is in a relax state, but the SOC is rising, it appears to be either in charge or discharge the whole time.

Cell Terminate voltage is 2500mV, what is terminate voltage for a single cell in your application?

Regards,

Evan

Hi, 
The log file for the GPCCHEM tool provide from learning cycle.

The relax state is at the end of the log (between 29/03 and 02/04). There is a slight drop voltage during the 3-day break (29.06V to 28.58V so 70mV per cell). And if there was a disharge, we an assume decrease in SOC and not an increase.

Cell Terminate voltage for a single cell = 2300mV (cut off protection). We chose 2500mV to have a margin before the power cut for the BMS.

Best regards

Hi,

In the log file you sent, do not see where the SOC jumped from 90% to 100%.

SOC is orange, Current is blue.

Do you have a log file with the SOC jump?

Regards,

Evan

Hello Evan, 

You can see the SOC jump at the end of the first sheet.

I did not include the SOC jump in the curves because of the too large temporality.

Regards,

Hi,

Can you provide a log file with the SOC jump?

Regards,

Evan

Hi, 

It was in my first message.
Here the log :6663.2024-03-29T10-21-13.xlsx

If you prefer, the csv file : 2024-03-29T10-21-13_monitor.csv

Hi,

Please allow me some time to look into this.

Thanks,

Evan

Hi Evan, 

About the temperature, it's thermistor of the BQ28z610. There is not such a drastic change. Between the two measures several days ago. That is a long relaxation.

Isn't easy to choice the good load select. Do you have a document to help on that ?

Choosing the 6 bothers me because the current requested by our customer’s application is not fixed.

And, I do not make the link between this register and the problem defined upstream. Because the "load selec" allows to refine the accuracy of the Remaining Capacity and not the SOC at the end of the charge.

Regards,

Hello,

Evan is out of office today, he will get back to you tomorrow. 

Regards,

Nick Richards