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Original question:

BQ34Z100-R2: Learning status bit not updating to 5 after following learning cycle steps for an LFP pack

BQ34Z100-R2: Update Status = 4 after charging and resting for a day

John Uriell
Prodigy 80 points
Part Number: BQ34Z100-R2
Other Parts Discussed in Thread: GPCCHEM

Tool/software:

Hello, while following the first charging stage of the learning cycle where update status is supposed to update from 4 to 5 and VOK is supposed to drop to 0 as the device does a Qmax update. I've charged my Molicell P30B, which I've programmed for using CHEM_ID = 2145 to just over 4.1V and let sit for a day and VOK = 1 still. In the log Single_Cell_Log.log it looks like FIRSTDOD = 1 but never dropped back to FIRSTDOD = 0. According to the technical reference document FIRSTDOD is "Set when RELAX mode is entered and then cleared upon valid DOD measurement for QMAX update or RELAX exit," so this seems to indicate that it has gone into RELAX mode, but hasn't done a QMAX update. 

I've been working at this for a couple days and haven't been able to figure out why it hasn't done the QMAX update and moved on to the next step of the learn cycle. What should I do? Thanks.

  • 0
    TI__Mastermind 26255 points

    Hi,

    Can you share the GPCCHEM report generated to get the ChemID match and the data submitted?

    Regards,

    Diego

  • 0 in reply to Diego
    Prodigy 80 points

    I'm using CHEM ID 0x2145 which corresponds to the sony us18650vc7 and the physical battery I am using is a Molicell P30B (so the programmed chemistry seems to match the real thing)

    I left it over the weekend and it has finally seemed to do a Qmax update, but Update Status = 04 still. This post here: https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1320753/bq34z100-r2-learning-status-bit-not-updating-to-5-after-following-learning-cycle-steps-for-an-lfp-pack seems to mention the same issue where the update status isn't changed: 

    "

    1. Started with a full battery. Sent a reset command. RUP_DIS turned ON. Started discharging. DSG flag turned ON during discharge. Finished discharging. FIRSTDOD turned ON. BATLOW turned ON.
    2. After waiting for a few hours, RUP_DIS turned OFF, FIRSTDOD turned OFF, and REST turned ON
    3. Charged the battery to ~31V and auto terminated when charging current was < 0.005 A. VOK turned ON. FC turned ON after charging finished. FIRSTDOD turned ON again. BATLOW turned OFF. CHG turned OFF. SOC1 turned OFF. SOCF turned OFF. REST is OFF.
    4. Waited for a few hours and the following happened: VOK turned OFF. FC turned OFF. CHG turned ON. SOCF turned ON. SOC1 turned ON. FIRSTDOD turned OFF. REST turned ON.
    5. As far as the status bits, whatever you mentioned is exactly what happened. However, Learning Status is still 4 at this point!
    6. I still went ahead and discharged it @ C/5 (1.34 A). As it was charging, VOK turned ON again. DSG turned ON. SLEEP turned OFF. REST turned OFF.
    7. After discharging was complete (down to 22V), I waited for a few hours, SLEEP turned ON, VOK turned OFF, DSG turned OFF, BATLOW turned ON, CF turned OFF and REST turned ON. Luckily this time though, and finally, Learned Status turned 5!!
    8. Started charging a little higher than C/5 (~1.4 Amps). CCA turned ON. VOK turned ON. SLEEP turned OFF. BATLOW turned OFF. BATHI turned ON. FIRSTDOD turned ON.
    9. Charging auto terminated. Waited for a few hours. SLEEP turned ON. VOK turned OFF. FIRSTDOD turned OFF. REST turned ON. Learned Status is still 5.

    Currently, I am going through another discharging step trying to chase Learned Status 6.

    "

    Should I discharge the battery at C/5 anyway? In expectation that Update Status will increment?

    Thanks.

  • 0 in reply to John Uriell
    TI__Mastermind 26255 points

    Hi,

    How do you know the ChemID is an ok match if you are using different cells?

    If you have not used the GPCCHEM tool I recommend you use that to get a chemID match.

    A successful learning cycle cannot be completed without a valid chemid match.

    Regards,

    Diego

  • 0 in reply to Diego
    Prodigy 80 points

    8055.roomtemp_rel_dis_rel_2.csv

    Moli_P30B_new_report.zip

    Fullscreen 7077.GPC_report.txt Download 
    Chemistry ID selection tool, rev=2.54		
		
Configuration used in present fit:		
ProcessingType = 2		
NumCellSeries = 1		
ElapsedTimeColumn = 0		
VoltageColumn = 1		
CurrentColumn = 2		
TemperatureColumn = 3		
		
Best chemical ID : 2145	Best chemical ID max. deviation, % : 1.82	
		
		
		
Summary of all IDs with max. DOD deviation below 3%		
		
Chem ID	max DOD error, %	Max R deviation, ratio
2145	1.82	7.96
2144	1.97	2.44
5377	2.07	0.86
2085	2.43	2.5
5936	2.9	0.1
		
Max. deviations for best ID is within recommended range. Chosen best chemical ID is suitable for programming the gauge.		
		
		
Selection of best generic ID for ROM based devices like bq274xx		
		
		
Device / Family #1		
Generic Chem ID	Device/ Voltage/ Chemistry	max DOD error, %
3142	bq27421-G1D: 4.4V LiCoO2	21.03
354	bq27411-G1C: 4.35V LiCoO2	23.56
128	bq27421-G1A: 4.2V LiCoO2	27.53
312	bq27421-G1B: 4.3V LiCoO2	33.68
Best generic ID 3142		
Warning: Generic ID Deviation is so high that it is most likely due to anomaly in the data. Please check that data files have recomended format, units and test schedule		
		
		
Device / Family #2		
Generic Chem ID	Device/ Voltage/ Chemistry	max DOD error, %
1202	bq27621: (default) 4.2V LiCoO2	23.18
1210	bq27621:  (ALT_CHEM1) 4.3V LiCoO2	23.29
354	bq27621:  (ALT_CHEM2) 4.35V LiCoO2	23.56
Best generic ID 1202		
Warning: Generic ID Deviation is so high that it is most likely due to anomaly in the data. Please check that data files have recomended format, units and test schedule		
		
		
Device / Family #3		
Generic Chem ID	Device/ Voltage/ Chemistry	max DOD error, %
3142	bq27426: (ALT-CHEM2) 4.4V LiCoO2	21.03
1202	bq27426: (ALT_CHEM1) 4.2V LiCoO2	23.18
3230	bq27426: (default) 4.35V LiCoO2	23.63
Best generic ID 3142		
Warning: Generic ID Deviation is so high that it is most likely due to anomaly in the data. Please check that data files have recomended format, units and test schedule		
		
		
Warning: Last OCVpoint has non-zero current I=  -0.2996490425 Please make sure you have a 5 hr relaxation period after the end of discharge.

    Here is the data I used for the the GPCCHEM tool and the results I got.

    The results told me to use a chemistry that corresponds to the Sony US18650UC7, which has the same 18650 package, the same nominal voltage of 3.6V, possesses a similar nominal capacity (3500mAh vs 3000mAh) to the Molicell P30B I am using. They're also both Lithium Ion batteries that seem to be using Ni-Co-Mn chemistry. So, I think it's highly probable that this is either the right chemistry, or at least pretty close to it. 

  • 0 in reply to John Uriell
    TI__Mastermind 26255 points

    Hi,

    Thanks for confirming that you have the correct ChemID.

    It has been seen that the update status will get stuck. If you have gotten a Qmax update then you have reached update status 0x05, you can continue with the learning cycle process and see if you ra tables update, if your ra tables update you have reached learn status 0x06 and have completed a learning cycle.

    Regards,

    Diego

  • 0 in reply to Diego
    Prodigy 80 points

     

    Would it be possible to get a webex meeting with you? Or with someone? Is this the correct place to ask?

    I've asked for assistance and been told there is no FAE assigned to my location. 

  • 0 in reply to John Uriell
    TI__Mastermind 26255 points

    Hi,

    I do not think a meeting is necessary at this point.

    Please continue to work with Danilo on cordinating a meeting.

    If you have further questions regarding the learning cycle you can ask here.

    Regards,

    Diego

  • 0 in reply to Diego
    Prodigy 80 points

    I've attempted the learn cycle a couple more times with the following parameters:

    • Design Capacity = 3000mAh
    • Design Energy = 1080cWh
    • Design Voltage = 3600mV
    • Cell Charge Voltage T1-T2 and T2-T3 = 4200mV
    • Taper Current = 100mA
    • Cell Terminate Voltage = 2900
    • Chg current threshold = 75mA
    • Dsg current threshold = 60mA
    • Quit current = 40mA

    On charging and discharging, the VOK ad RUP-DIS bits seems to become 0 and REST = 1 after resting, but Update Status still does not seem to change from 4 to 5.

    Here is the log from the most recent discharge I've done: 7s1p Learn Cycle #3 part 3 discharge#2.log

    I was following what was done in this post ( https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1320753/bq34z100-r2-learning-status-bit-not-updating-to-5-after-following-learning-cycle-steps-for-an-lfp-pack ) wherein the learn status updated after the second discharge cycle instead of the first charge cycle, because after resting after my first charge cycle my learn status did not increment to 5 either:

    "

    6. I still went ahead and discharged it @ C/5 (1.34 A). As it was charging, VOK turned ON again. DSG turned ON. SLEEP turned OFF. REST turned OFF.

    7. After discharging was complete (down to 22V), I waited for a few hours, SLEEP turned ON, VOK turned OFF, DSG turned OFF, BATLOW turned ON, CF turned OFF and REST turned ON. Luckily this time though, and finally, Learned Status turned 5!!

    "

  • 0 in reply to John Uriell
    TI__Mastermind 26255 points

    Hi,

    From the log file sent it appears that you only discharge to empty and let the battery rest. You also said VOK and Rup-Dis were cleared at this point. Update status will not flip from 4 to 5 at this point. You need to charge to full, relax, then discharge to empty. The steps are in the document provided below.

    Achieving The Successful Learning Cycle (tij.co.jp)

    Regards,

    Diego

  • 0 in reply to Diego
    Prodigy 80 points

    I don't have the earlier parts of the log because our IT department restarted my computer while it was resting overnight. I only have the discharge to empty from this step:

  • 0 in reply to John Uriell
    TI__Mastermind 26255 points

    Hi,

    Understood, this is the second time discharging.

    When both the VOK and RUP_DIS cleared while the device was in rest, did you get a Qmax update.

    Update status has been seen to get stuck on this device before. If you have gotten a Qmax update you have reached update status 5 and can continue until your Ra tables update at which you will have reached update status 6 and completed the learning cycle. 

    Regards,

    Diego