BQ34Z100 design capacity

Slim123

Other Parts Discussed in Thread: GPCCHEM, BQSTUDIO, BQ34Z100-G1

Hi,

We are having a Calb 100Ah pack for our testing. Due to there is no battery chemistry for 100Ahr Calb, will there be any issue if we are setting the design capacity to be 10000(there is a x10 scale factor) but selecting Calb 40Ahr cell (ChemID: 0437)for the pack chemistry?

Can we use the chem ID for Calb 40Ahr on 100Ahr Calb?

Thanks.

over 9 years ago

0 Slim123 over 9 years ago

Expert 1210 points

Hi is there any update?

Thanks

0 ThomasCosby over 9 years ago in reply to Slim123

TI__Guru 73830 points

The capacity listed with the ChemID is not important. You will need to use the GPCCHEM tool to verify that the ChemID is a good match for you cell. You can use 10x scaling, but 4x scaling will also work for a 100Ah pack.

www.ti.com/.../GPCCHEM

0 Slim123 over 9 years ago in reply to ThomasCosby

Expert 1210 points

Thanks Tom.

We seen an issue where we start to discharge the 100Ahr pack at 62% but it took an hour to discharge it down to 0% which has consumed 109 AHrs of discharge capacity.

I have attached the log file here. Do you have any idea on whats has gone wrong?

Discharge 100Ahr Pack.xlsx

0 ThomasCosby over 9 years ago in reply to Slim123

TI__Guru 73830 points

The SOC should not have been at 62% at the beginning of discharge. You will need to verify that the ChemID is a good match to your cell and run the optimization cycle to make sure that we have a good setup. It will also be good to log data using bqStudio to provide more data to analyze the issue.

0 Slim123 over 9 years ago in reply to ThomasCosby

Expert 1210 points

Sorry Tom, forgot to mention the battery has gone through several charge and discharge cycles previously. The SOC starting at 62% because it was left without charger for some time and we start to discharge it when SOC drops to 62%.

Does the data appear to be improper chem ID issue?

0 ThomasCosby over 9 years ago in reply to Slim123

TI__Guru 73830 points

It looks it could be a ChemID problem or a Qmax and Ra table problem. The SOC should be closer to 95% at the voltage levels in the log file, for ChemID 437.

0 Slim123 over 9 years ago in reply to ThomasCosby

Expert 1210 points

In fact we have a learned GG file for the 40AHr pack with chem ID of 0437, where the Qmax recorded is close to 4000 because there is a x10 scaling.

We put this GG file into the 100AHr pack with same chemistry by changing the Qmax and the design capacity. We expect the bq data will slowly adjust to match with the new pack capacity after several cycles. The design capacity & Qmax were changed to 10000 with a x10 scaling.

If it is fine to do so, is it we should change the scaling to x25 (4000X25 = 100000mAh)instead without changing the parameters in the learned GG file?

0 ThomasCosby over 9 years ago in reply to Slim123

TI__Guru 73830 points

Did you also scale the current when you calibrated? I have a applications note on scaling on the bq34z100-G1 website.

0 Slim123 over 9 years ago in reply to ThomasCosby

Expert 1210 points

Yes. We have scaled the current accordingly during calibration. You mentioned in previous reply that it is fine if design capacity does not match with the capacity stated on the chem ID. Wondering what does chem ID do with the gauging? I tested by importing different ID into a GG, the changes seen is on the RA table only

0 ThomasCosby over 9 years ago in reply to Slim123

TI__Guru 73830 points

The ChemID does not contain any capacity information. It contains the OCV and Ra tables. The capacity data is set when the optimization cycle is run.

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BQ34Z100 design capacity