BQ27Z561: Learning Cycle Failure (Update Status stuck at 0x05)

Adam Johnson

Part Number: BQ27Z561
Other Parts Discussed in Thread: BQSTUDIO

I have a colleague who is working on a battery pack design with the BQ27Z561EVM-011 and 6 Moli INR18650A lithium cells in parallel (datasheet attached). He is trying to do a learning cycle, and is not using the Gauge Development Kit (GDK).

This is the sequence he is following:

Send GAUGE_EN command.
Start with discharged cells (3.3V). Update status is 0x04.
Fully charge the cells (4.0V).
Relax the cells until VOK is cleared, REST is set, QMAX is toggled, and update status is 0x05.
Discharge the cells with 1.5A load until the cells' voltage is 3.3V.
Relax the cells for 5 hours.

At the end of step 6, VOK is cleared and REST is set, but update status is not updated to 0x06, so the learning cycle fails. What might we be doing wrong?

Below are the parameters we're using in the fuel gauge. I've also attached the config.gg and log files from Battery Management Studio.

Low Temp Charging Voltage	4000 mV
Standard Temp Charging Voltage	4000 mV
High Temp Charging Voltage	4000 mV
Rec Temp Charging Voltage	4000 mV
Charge Termination Taper Current	300 mA
Discharge Current Threshold	60 mA
Charge Current Threshold	75 mA
Quit Current	40 mA
Design Capacity	15000 mAh
Design Capacity	5400 cWh
Design Voltage	3600 mV
FC Set Voltage Threshold	4000 mV
FC Clear Voltage Threshold	3900 mV
TC Set Voltage Threshold	4000 mV
TC Clear Voltage Threshold	3900 mV
State Qmax Cell 1	2500 mAh
State Cell 1 Chg Voltage at EoC	3990 mV
State Current at EoC	300 mA
IT Cfg Term Voltage	3300 mV

0901-UN-INR18650A-ATC-R6A1.pdf

7288.1407.gg.csv

0624.1407.log

over 5 years ago

0 Wyatt Keller over 5 years ago

TI__Guru** 105590 points

Hello Adam,

I haven't had time to look through your log files yet, but one observation from the data you provided would be the voltage range is fairly small, during the learning cycle there needs to be a 90% change in total charge which is based on your design capacity.

You can reference the battery specs to see the full voltage range of the batteries, even if you do not plan to use the full range it would be best to do the learning cycle on the full voltage range.

You can check by integrating the current during your log, if it's not 90% of design capacity the gauge won't update.

Sincerely,

Wyatt Keller

0 Darshan Goswami over 5 years ago in reply to Wyatt Keller

Prodigy 190 points

Thanks, Wyatt Keller.

I will trigger the learning cycle according to your suggestion. I will use single battery cell to complete the learning cycle instead of 6 parallel (which used in a real application).

0 Wyatt Keller over 5 years ago in reply to Darshan Goswami

TI__Guru** 105590 points

Hello Darshan,

Sounds good, let me know if this resolves your problem.

Sincerely,

Wyatt Keller

0 Darshan Goswami over 5 years ago in reply to Wyatt Keller

Prodigy 190 points

Hi Wyatt, Wyatt Keller

I have completed the learning cycle and the last update status is 06. You can find full learning cycle log from (full_LearningCycle.log) file. Then I have trigger one more charge - relax- discharge cycle and now update status is 0E. I have attached this cycle in the afterSuccessLearningCycle.log file.

I have also attached before and after data memory configuration in before_LearningCycle.gg.csv and after_LearningCycle.gg.csv.

Can you please confirm that Is it performed successfully or not?

Question: I am going to create a golden image. But I have performed a learning cycle on single-cell but my application cell pack is 1s6p (6 parallel cells). So, Should I need to trigger new learning cycle for the 1s6p cell pack or this learning cycle is correct? Please suggest. How can I move further?

afterSuccessLearningCycle.log after_LearningCycle.gg.csv before_LearningCycle.gg.csv full_LearningCycle.log

0 Wyatt Keller over 5 years ago in reply to Darshan Goswami

TI__Guru** 105590 points

Hello Darshan,

Your logs look good and you have gotten the 0x0E update status. I would recommend you run the learning cycle on the full pack with 1S6P so the gauge can update the resistance tables more accurately in the golden image when you upload it to all your boards in production.

Sincerely,

Wyatt Keller

0 Darshan Goswami over 5 years ago in reply to Wyatt Keller

Prodigy 190 points

I have started learning cycle on 1s6p cells before this learning cycle but failed. I have already mentioned in the first question.

Can you please help me to find out what parameters I need to change for the 1s6p cells pack instead of a single cell? So I can trigger the learning cycle for 1s6p cells pack.

0 Wyatt Keller over 5 years ago in reply to Darshan Goswami

TI__Guru** 105590 points

Hello Darshan,

You will need to scale the design capacity and any other parameters you used for the capacity. Voltages and calibrations should all be the same.

Sincerely,

Wyatt Keller

0 Darshan Goswami over 5 years ago in reply to Wyatt Keller

Prodigy 190 points

Hi Wyatt Keller

Should I need to use different Fuel gauge for the second learning cycle? or I can use same Fuel gauge for multiple learning cycles?

The last update status is 0x0E (learning cycle success) and I have triggered the second learning cycle on full cell pack(1s6p). Before starting the learning cycle I have sent GAUGE_EN (0x21) and RESET (0x41) on the same Fuel gauge. But update status is not updated to 0x00 or 0x04. It is the same 0x0E. How can I reset update status to 0x00 or 0x04 to start a new learning cycle?

0 Darshan Goswami over 4 years ago in reply to Darshan Goswami

Prodigy 190 points

Hi Wyatt Keller

Can you help me to figure out this issue? I am waiting for someone's suggestion.

0 Kang Kang over 4 years ago in reply to Darshan Goswami

TI__Mastermind 24870 points

Hello Darshan,

You will need to change update status back to 0x04 or 0x00 and then repeat the learning cycle.

Thanks!

0 Darshan Goswami over 4 years ago in reply to Kang Kang

Prodigy 190 points

Thanks for the reply.

I know we need to change the update status to 0x00/0x04 to start the new learning cycle but How can I set it to 0x00/0x04? That is my query which stated earlier. I have sent GAUGE_EN (0x21) and RESET (0x41) to the Fuel gauge. But update status is not updated to 0x00 or 0x04.

Can you suggest me what I can do?

0 Darshan Goswami over 4 years ago in reply to Darshan Goswami

Prodigy 190 points

Power management forum

Can anyone help me to figure out this issue?

0 Wyatt Keller over 4 years ago in reply to Darshan Goswami

TI__Guru** 105590 points

Hello Darshan,

I apologize for the delay, if you are simply trying to reset the update status back to 0x04 or 0x00 you can manually change it in data memory within bqStudio.

Sincerely,

Wyatt Keller

0 Darshan Goswami over 4 years ago in reply to Wyatt Keller

Prodigy 190 points

Thanks, Wyatt Keller

I will do this and trigger the learning cycle.