BQ34Z100-R2: Battery Learning Cycle for Golden file Creation.

Shashi Rai

Prodigy 120 points

Part Number: BQ34Z100-R2
Other Parts Discussed in Thread: BQSTUDIO, BQ34Z100, GPCCHEM

Tool/software:

Hi,

We are using the BQ34Z100-R2 for one of our power bank and BMS project.

We have started the learning cycle of the cell pack with below considerations.

1) Cell Type - Lithium-Ion 18650 ( CHAM - 3450 mAh)

2) Cell configuration - 5S4P

3) Design Voltage - 18V ( Single voltage consideration 2.9V(min) - 3.6V (Typ) - 4.2V(Max))

4) Total Design capacity - 12400 mAh

5) Discharge Rate C/10 - 1200 mA

6) Charging Rate ~ 2500A

7) Term dicharge voltage - 3100 x 5 = 15500 mV

We have initiated the learning cycle for our Lithium-Ion cell and would like to clarify a few observations encountered during the process.

Chem ID Selection:

The Chem ID for our cell is available in the beta version of BQStudio, so we selected it and proceeded with the learning cycle. Kindly confirm if this is acceptable.
Discharge Cycle Observation:

We completed the first discharge cycle successfully and kept the setup in relax mode for approximately 14 hours overnight. As per TI document “4863 - How to Complete a Successful Learning Cycle for the BQ34Z100”, the required status bits were set appropriately. However, we noticed that:
- The FC (Full Charge) bit was set, and the battery status showed 100%, which seems unusual.
- During the discharge cycle, the SoC jumped from 100% at 20.5V directly to 0% at 19.5V, and remained at 0% throughout the rest of the discharge down to 15.5V.
- During the relax period, the SoC jumped back to 100% (at around 14.7V) after approximately 1 hour.
Please advise if this behavior is expected or if it indicates a configuration issue.
Charging Cycle Behavior:

As per the procedure, we started the charging cycle. The VOK bit was set correctly after connecting the charger. However, we are concerned about the premature setting of the FC bit. Kindly suggest if any adjustments are needed here.
Capacity Values:

We also observed that the Remaining Capacity and Full Charge Capacity values appear to be too low and not in line with our battery's specifications (refer to the attached image). Your guidance on this would be appreciated.

For your reference i have attached the logs and the exported registers value with this mail. Please find the attchment.

4 months ago

0 Shashi Rai 4 months ago

Prodigy 120 points

BQ_Learning_Parameters_settings.gg.csv Discharge_20_5_25.xlsx

0 Alan Frias 4 months ago

TI__Mastermind 27405 points

Hello Shashi,

Shashi Rai said:
The Chem ID for our cell is available in the beta version of BQStudio, so we selected it and proceeded with the learning cycle. Kindly confirm if this is acceptable.

-Typically we recommend using the GPCCHEM tool regardless if you see your cell within the ChemID library due to difference between vendors

Shashi Rai said:
Capacity Values:

We also observed that the Remaining Capacity and Full Charge Capacity values appear to be too low and not in line with our battery's specifications (refer to the attached image). Your guidance on this would be appreciated.

Shashi Rai said:
Discharge Cycle Observation:

We completed the first discharge cycle successfully and kept the setup in relax mode for approximately 14 hours overnight. As per TI document “4863 - How to Complete a Successful Learning Cycle for the BQ34Z100”, the required status bits were set appropriately. However, we noticed that:

The FC (Full Charge) bit was set, and the battery status showed 100%, which seems unusual.

During the discharge cycle, the SoC jumped from 100% at 20.5V directly to 0% at 19.5V, and remained at 0% throughout the rest of the discharge down to 15.5V.

During the relax period, the SoC jumped back to 100% (at around 14.7V) after approximately 1 hour.

Please advise if this behavior is expected or if it indicates a configuration issue.

Charging Cycle Behavior:

As per the procedure, we started the charging cycle. The VOK bit was set correctly after connecting the charger. However, we are concerned about the premature setting of the FC bit. Kindly suggest if any adjustments are needed here.

-If you were able to complete a learning cycle can you verified through a discharge/relax/charge cycle to see if it is behaving as expected

Shashi Rai said:
Capacity Values:

We also observed that the Remaining Capacity and Full Charge Capacity values appear to be too low and not in line with our battery's specifications (refer to the attached image). Your guidance on this would be appreciated.

-After reviewing your .log file your learned status is stuck at 04 meaning that learning cycle was not successfully completed. Please reference this FAQ below

FAQ:
https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1263138/faq-why-is-the-update-status-not-updating-from-4-to-5

Thank you,
Alan

0 Shashi Rai 4 months ago in reply to Alan Frias

Prodigy 120 points

Hi,

Thanks for the response, as suggested, We have reinitiated the Learning cycle.

As DOD0 seen in logs is stay at 0 value all the time. I don't getting its right or wrong.
We will moving for the another iteration.

Please confirm for the calculations as we have considered is right or need any changes on the same.

1) Cell Type - Lithium-Ion 18650 ( CHAM - 3450 mAh)

2) Cell configuration - 5S4P

3) Design Voltage - 18V ( Single voltage consideration 2.9V(min) - 3.6V (Typ) - 4.2V(Max))

4) Total Design capacity - 12400 mAh ( (13400 mAh) 10% reduced capacity considered due to discharge level of 2.9V instead of 2.5V rated in cell datasheet)

5) Discharge Rate C/10 - 1200 mA

6) Charging Rate ~ 2500A

7) Term dicharge voltage - 3100 x 5 = 15500 mV

Additionally, as per our observation

During the discharge cycle, the SoC jumped from 100% at 20.5V directly to 0% at 19.5V, and remained at 0% throughout the rest of the discharge down to 15.5V.
During the relax period, the SoC jumped back to 100% (at around 14.7V) after approximately 1 hour.

To Address the above point do we need to set the Lock_0 bit as mentioned in Reference manual document "BQ34Z100-R2 Technical Reference Manual (Rev. A) (ti.com)"

Please suggest.

Thanks & Regards,

Shashikumar Rai

0 Alan Frias 4 months ago in reply to Shashi Rai

TI__Mastermind 27405 points

Hello Shashikumar,

Shashi Rai said:
3) Design Voltage - 18V

-Your design voltage would be your max charging voltages times the amount of cells in series

Shashi Rai said:
Total Design capacity -

-Typically we don't recommend derating your total capacity and we recommend following your cell's datasheet capacity and times it by the amount of cells in parallel.

Shashi Rai said:
6) Charging Rate ~ 2500A

-Assuming that it is 2500mA, but typically we recommend C/2 but you can also use whatever is the recommend charging rate

Shashi Rai said:
During the discharge cycle, the SoC jumped from 100% at 20.5V directly to 0% at 19.5V, and remained at 0% throughout the rest of the discharge down to 15.5V.

-This is most lilkely hinting that your parameters are set up wrong or most likely that your chemID is wrong. Make sure that your critical parameters are set correctly. Design Capacity, Design Voltage, Charge Term Taper Current, Dsg Current Threshold, Chg Current Threshold, Quit Current and Term Voltage

Thank you,
Alan

0 Shashi Rai 3 months ago in reply to Alan Frias

Prodigy 120 points

Hi,

We are designing for two battery pack variants: 5S4P and 4S2P.
We have tested the setup with both configurations, but the issue remains the same in both cases.

Current Test: 4S2P
Cell Pack Voltage Range: 12.0 V to 16.8 V

Despite configuring the parameters correctly, we are observing abnormal behavior:
At 12.0 V, BQStudio sets the Full Charge (FC) flag and shows 100% SoC, which is not expected.

I have attached the exported parameter file for the 4S2P configuration.
Also enclosed is the cell pack datasheet for your reference.

We are currently stuck and unable to proceed further.
Your guidance and support would be highly appreciated.

100wh_confi.xlsx WI(Q)-RD-D-143 A1 CMINR18650F9E-3450mah-Specification.pdf

Thanks & Regards,
Shashikumar Rai

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BQ34Z100-R2: Battery Learning Cycle for Golden file Creation.