BQ34Z100-G1: CHG bit never set

Akshay Bhagat

Part Number: BQ34Z100-G1
Other Parts Discussed in Thread: GAUGEPARCAL, GPCCHEM,

I am running a learning cycle on the Bq34z100G1 as specified by Thomas here:https://e2e.ti.com/support/power_management/battery_management/f/180/t/300700

The discharge cycle runs fine with the OCVTAKEN flag setting

However, during the charge cycle the CHG bit is not set. Also, the VOK bit is cleared during charge. This leads me to believe that the Q updates are not happening.

PFA the gg param file. The current has been scaled by 4 during calibration.The log file is for the first high current discharge at >c/8 . However, the OCVTAKEN flag is not set.

7801.params_test1.xls

5504.7_19.log

over 8 years ago

0 Onyx Ahiakwo over 8 years ago

TI__Guru* 76230 points

Hi Akshay,
Your log and gg files would be useful to see what is going on. Also, Can you make sure your charge current thresholds are set correctly?

thanks
Onyx

0 Akshay Bhagat over 8 years ago in reply to Onyx Ahiakwo

Prodigy 140 points

The .gg file is attached above saved as .xls

0 Onyx Ahiakwo over 8 years ago in reply to Akshay Bhagat

TI__Guru* 76230 points

Hi Akshay,
your log file only shows a discharge current. There is no way the chg flag will be set if you are not charging.
thanks
Onyx

0 V S86 over 8 years ago in reply to Onyx Ahiakwo

Prodigy 30 points

Akshay is traveling. In his absence, I have attached the log file for the charge cycle to this message.

The individual cells are charging as can be seen from the increasing voltage, but the charge bit doesnt set, nor do the Q updates occur.

Please advice.

7_21_charge.txt

0 Onyx Ahiakwo over 8 years ago in reply to V S86

TI__Guru* 76230 points

Your log files does not show current tapering to meet the taper current condition. You need to meet the primary charge termination conditions for the FC flag to set. pls see the TRM
thanks
Onyx

0 Batt over 8 years ago in reply to Onyx Ahiakwo

TI__Mastermind 42535 points

Akshay,

Please send me your srec file. How did you select your battery chem ID for the gauge? To understand our gauges better, please refer to http://www.ti.com/lit/an/slua597/slua597.pdf and http://www.ti.com/lit/an/slua777/slua777.pdf

0 Batt over 8 years ago in reply to Batt

TI__Mastermind 42535 points

Your chg is never set simply because xchg is set in the flags. XCHG will be set because your external temp reads -39C. Your df charge inhibit temp low is 0C. You need to attach a thermistor or use the internal temp register to read the temp by settings configuration: registers: pack configuration:temps bit to 0.

0 Akshay Bhagat over 8 years ago in reply to Batt

Prodigy 140 points

Upon removing the TEMPS flag or adding an external thermistor the CHG bit did set upon charging. However, upon starting a learning cycle on a fully discharged battery with the IT Enable Command the CHG bit didn't set once again. The temperature was now correct.

See the current log file for reference. Parameters are same as in the initial upload.

0802_chargecycle.log

0 Batt over 8 years ago in reply to Akshay Bhagat

TI__Mastermind 42535 points

FC is set and your RSOC is 100% and your Remcap and FCC are the same. Therefore CHG will not be set.

0 Akshay Bhagat over 8 years ago in reply to Batt

Prodigy 140 points

I have 2 questions regarding the same:
1. The Gauge seems to be showing an incorrect capacity. Does the CHG bit have to set for the gauge to learn on the charging cycle to go from status x04->x05??
Even when the battery goes from empty to FCC it does not update the status.

2. Is there a method to set the capacity Remcap to 0 on a fully discharged battery via a Command. How do i correct the wrong capacity before stating a learning cycle??

0 Batt over 8 years ago in reply to Akshay Bhagat

TI__Mastermind 42535 points

1. Yes, CHG bit setting indicates that you have crossed charging threshold and that the accumulator is counting passed charge.

2.No, there's no such command. It is initially done by computing the DOD value corresponding to the voltage the battery is at. Did you characterize your cell using the gaugeparcal tool?

0 TEC over 8 years ago in reply to Batt

Expert 2475 points

The Ra table indicates that you are still using the default ChemID. You should use the GPCCHEM tool to find a ChemID match for the cells as BATT suggested. You can also set the Load Mode = 0 temporarily to see whether that helps with FCC. The Ra table has less effect on the capacity simulation when using constant current.

0 Onyx Ahiakwo over 8 years ago in reply to Akshay Bhagat

TI__Guru* 76230 points

Akshay
1. if you are charging the battery, the chg bit has to be set. You need to set your taper current in data flash to be greater than the chg current threshold which in turn should be greater than your quit current.

2. No there isn't. You should care about the capacity until learning has been completed.

thanks
Onyx

0 Akshay Bhagat over 8 years ago in reply to Onyx Ahiakwo

Prodigy 140 points

From my param file you can see the
taper current:100mAmp
chg current threshold: 75mAmp
quit current:40mAmp

So I think that is as it should be.

Sometimes during discharge both the charge and discharge bits set.

0 TEC over 8 years ago in reply to Akshay Bhagat

Expert 2475 points

The CHG flag in the bq34z100-G1 means that charging is allowed and not necessarily that charging is in process. That is why you will see it set low after charge termination, although charging mat still be in process. In this case the pack is discharging, but charging is also allowed since the pack is not fully charged.

0 Akshay Bhagat over 8 years ago in reply to TEC

Prodigy 140 points

I have managed to sucessfully complete a learning cycle. However, I still have one problem.

In the voltage calibration step previously I get the following error. I calculated the voltage divider value by hand, but i believe it is not very accurate.

I have two questions regarding the same:

1. When I enter voltage across bat+ and bat- which is 22,000 mV, I get the error: Calibration cell voltage entered is out of range. This value is in millivolts. Please check value and retry.

Should this be voltage per cell, in my case 22,000/6 as I have a 6s battery?

2. When I enter the per cell voltage, i.e. 3666 mV it starts calibration but errors out with error:

Calibration-A read of data written failed comparison.

I have tried using the new bq config file suggested by Thomas here, but it did not fix the issue.

https://e2e.ti.com/support/power_management/battery_management/f/180/t/567747

Thanks.

0 Onyx Ahiakwo over 8 years ago in reply to Akshay Bhagat

TI__Guru* 76230 points

Hi Akshay,
It should be your stack voltage. pls see the voltage callibration procedure in the user guide in the link below:

www.ti.com/.../sluu904a.pdf

thanks
Onyx

0 TEC over 8 years ago in reply to Onyx Ahiakwo

Expert 2475 points

Also make sure that IT is not enabled and you can try using the .bqz file referenced in this link.

e2e.ti.com/.../2243612

Power management

Power management forum

BQ34Z100-G1: CHG bit never set