BQ40Z50EVM-561: BQ40Z50EVM-561

Adding to this problem I am not able to get the battery charged again. I have issued a reset command and if I press the WAKE button I get voltage on the output but I am not able to get it charging. The moment I release the WAKE button the output voltage disappears again.

Hello Bruce,

I have assigned someone to take a look at this. We will respond by the end of today.

Sincerely,

Wyatt Keller

Hello Bruce,

Can you share a .gg file from before and after the learning cycle attempt along with the BQStudio log of the learning cycle? Also make sure you have selected the best matching chem ID using GPCCHEM tool.

I suspect for your second issue your gauge is hitting the SDV point and trying to shutdown. Make sure you have adjusted the shutdown voltages to match your system.

Sincerely,

Wyatt Keller

GassGaugeSettings_cal.gg.zip50GassGaugeSettings_cal.gg.csv1GassGaugeSettings_cal.log

The ChemID of 413 was supplied to us by the battery manufacturer.

Hello Bruce,

I have taken a look at your logs. Here are my findings. Firstly, the LearnedStatus in the logs never changed from 0 which implies the reset command was never sent and the algorithm was not enabled so the gauge could not complete a learning cycle. I believe this is the main cause.

Additionally, I noticed some other problems that will affect learning. The value for your terminate voltage is set high at 9000 mV. Ensure all the relevant parameters from slua903 are correct. After all parameters are correct try the cycle again.

To ensure the correct Chem ID you could follow this FAQ:

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1100656/faq-how-do-i-find-a-chemistry-id-for-my-battery

Sincerely,

Erik Cura

Hi Erik,

I am having a new problem. I mentioned it earlier. The only time I can get a PACK voltage is when I press the WAKE button. As soon as I let it go the voltage disappears again. I have attached an updated LOG and gg.csv file.

Regards

Bruce

Wed Jun 29 15:02:18 NZST 2022

Device Version Info = 4500_2_08
BQZ Device Name = bq40z50R2
BQZ Firmware Version = V2_08_BLD50

Design Capacity = 12000
Design Voltage = 6400
Specification Info = 0x0031
Manufacturer Date = 1980-1-1
Serial Number = 0x0001
Manufacturer Name = Texas Instruments
Device Name = bq40z50-R2
Device Chemistry = LION

Sample,DateTime,ElapsedTime,ManufAccess,RemCapAlarm,RemTimeAlarm,BattMode,@Rate(@),@TimeFull,@TimeEmpty,@RateOK,Temperature,Voltage,Current,AvgCurr,MaxErr,RSOC,ASOC,RemCap,FullChgCap,RunTimeEmty,AvgTimeEmty,AvgTimeFull,ChgCurr,ChgVolt,BattStat,CycleCnt,MaxTurboPwr,SusTurboPwr,MaxTurboCurr,SusTurboCurr,SoH,OpStatA,OpStatB,TempRange,ChgStat,GaugeStat,ITStat,MfgStat,SafetyAlertAB,SafetyStatAB,SafetyAlertCD,SafetyStatCD,PFAlertAB,PFStatAB,PFAlertCD,PFStatCD,CellVolt1,CellVolt2,CellVolt3,CellVolt4,vBAT,vPACK,CellCurr1,CellCurr2,CellCurr3,CellCurr4,CellPower1,CellPower2,CellPower3,CellPower4,Power,AvgPow,IntTemp,TS1Temp,TS2Temp,TS3Temp,TS4Temp,CellTemp,FETTemp,GaugeTemp,FltRemQ,FltRemE,FltFullChgQ,FltFullChgE,NoLoadRemCap,TrueRemQ,TrueRemE,InitialQ,InitialE,TrueFullChgQ,TrueFullChgE,T_sim,T_ambient,RaScale1,RaScale2,RaScale3,RaScale4,CompRes1,CompRes2,CompRes3,CompRes4,PackGrid,LStatus,CellGrid1,CellGrid2,CellGrid3,CellGrid4,StateTime,DOD0_1,DOD0_2,DOD0_3,DOD0_4,DOD0 Passed Q,DOD0 Passed E,DOD0 Time,DODEOC_1,DODEOC_2,DODEOC_3,DODEOC_4,QMax1,QMax2,QMax3,QMax4,QMaxDOD0_1,QMaxDOD0_2,QMaxDOD0_3,QMaxDOD0_4,QMaxPassedQ,QMaxTime,Tk,Ta,RawDOD_1,RawDOD_2,RawDOD_3,RawDOD_4,CBTime1,CBTime2,CBTime3,CBTime4,CBDOD_1,CBDOD_2,CBDOD_3,CBDOD_4,CBTotalDODChg,SOH_FC_Q,SOH_FC_E,LogRowTime(ms),LogStatus
1,2022-06-29 15:02:27,8.133,0x6181,300,10,0x6081,0,65535,65535,1,21.0,6667,0,0,100,100,0,0,0,65535,65535,65535,0,0,0x02C0,0,-9718,-9718,-13312,-13312,0,0x6181,0x0000,0x08,0x0008,0xD0,0x0004,0x8000,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000,3334,3333,0,0,6639,4,0,0,0,0,0,0,0,0,0,0,20.9,21.0,20.9,20.9,21.0,21.0,20.9,21.0,0,0,0,0,9750,0,0,0,0,0,0,21.0,20.9,1000,1000,0,0,0,0,0,0,0,0,0,0,0,0,206,3072,3072,0,0,0,0,0,0,0,0,0,12000,12000,4400,4400,0,0,0,0,0,0,1.0,1000,3072,3072,0,0,0,0,0,0,0,0,0,0,0,0,0,1592,SUCCESS

I have managed to resolve this problem, by issuing a FET_EN command. I will now get back to doing the Learning Cycle.

1376.01-07-2022GassGauge.logI have now run the discharge cycle resulting in the [VOK] and [RDIS] to clear and [REST] to set. This all seems to be great, but I can't start the charging cycle, as when I do there is no current flowing into the battery.

351-7-2022GassGaugeSettings.gg.csv

Hello Bruce,

I apologize for the late response. I have taken a look at your logs and it seems that the flags show a that the FET_EN in MfgStat was disabled either by the host or a user through bqStudio. I suspect that this FET_EN toggling may have caused some kind of issue which caused it to stop charging.  However, this was a momentary toggle and the FET_EN is set to 1 after enabling charging so I am not sure what else would prevent charging. Please try again and ensure this bit does not toggle. 

Additionally, here are some other problems that I saw that are not related to charging.  I saw that the CUV protection was triggered. It seems that cell 2 minimum voltage is much lower than cell 1 triggering this protection. I believe this is because cell balancing was not initially enabled. Also, It seems that the gauge enable was not set before the start of the discharge based on the flags in Manufacturing Status. Also, LStatus is 0 for some time then changes to 4 later in the cycle signaling that the algorithm was not initialized for gauging at the beginning.

Sincerely,

Erik Cura

Hi Erik. I am running the test again but you mentioned that the balancing should be enabled. Just before I started the discharge the [BAL_EN] was set but as soon as I started the discharge ti changed to low.

Hello Bruce, 

The test should still be fine. The balancing was to try to mitigate the difference between the minimum cell voltages. 

Sincerely,

Erik Cura

I have once again managed to do a successful discharge but am now not able to start the charging to full again. I see that the [VOK] bit does also not set.What am I doing wrong.

0001-GassGauge-2022-07-06.zip10001-GassGaugeSettings2022-07-06.gg.csv480001-GassGaugeSettings2022-07-06.gg.csv

Hello Bruce,

I have taken a look at your logs. It seems like the gauge had been set to use the PCHG fet and not the CHG fet. This is because your minimum voltage went below the Precharge Start Voltage value in data memory. You can change this by setting the PCHG_COMM bit in the FET Options register in Data Memory.  

Additionally, the value for you terminate voltage is high at 7300 mV. It should be the desired terminal cell voltage X the number of cells in series. This will affect when the gauge detects a full discharge. I would adjust these parameters and start again.

Sincerely,

Erik Cura

Hi Erik,

Things are going a lot better. I will give you an update on Monday if I manage the get the learning cycle done by then.

Bruce

Hello Bruce,

That is good to know. I hope it completes by then.

Sincerely,

Erik Cura

Hi Erik,

Unfortunately the learning cycle has failed as the [FC] bit did not get set. Can you please check and let me know what I have done wrong. We are moving forward but unfrankly still not all the way.

Bruce

48-1-GassGaugeSettings2022-07-08.gg.csvGassGauge-2022-07-08.zip

Hello Bruce,

When looking at your charging profile it seems that the charging taper is not implemented correctly. This is especially important because LFP batteries relax into the flat region very quickly. This can cause errors when trying to get an OCV reading.  The logs show the OCVFR bit has set which means that if your voltage has fallen below the FlatVoltMax then the gauge will have a 48 hours wait before it takes a valid OCV reading. If you clear the bit then it will take a valid OCV reading when the dV/dt condition is met.  Please adjust the charge termination settings in Data memory and correct the charging taper. Information for the charging taper setting should be in the battery cell datasheet. After this is done please try again.

Sincerely,

Erik Cura

Hi Erik,

I am having difficulty understanding what I should be doing. Is there a document that describes, in a simple way, what you are talking about. Also is there a document that dives a detailed discretion of all the Data Memory locations to help me interpret what I should be putting in them. 

I have attached my battery datasheet in the dope that you may help me to find the correct values for the Data Memory. We will be discharing at 600mA and chnarging at 200mA to 1A with a cutoff at 100mA when under constant voltage charge.

BruceTAC_Datasheet_A12 Battery.pdf

Hello Bruce,

With regards to the FlatVoltMax parameter it is part of the CHEMID data. So you need to set the OCVFR bit to 0 in the IT Gauging Configuration setting in Data Memory in order for the gauge to take a valid OCV reading before the 48 hour wait time. Additionally, In the logs it shows that the FD bit was never set which means that the gauge never detected that the battery was fully discharged. This is due to your value of Term Voltage at 3650 mV. According to the data sheet that you sent the terminal voltage of your battery should be at 2000 mV for each cell so a value of 3650 mV would be too low. Due to the imbalance of your cells this value will never be reached as cell one hits the CUV protection first. This can be fixed by setting the gauge to cell based termination by setting the CELL_TERM bit in the IT Gauging Configuration in Data Memory.  This is based on the most recent gg file that was sent.

As for charging please adjust the Charge Term Taper Current to the battery specification(0.01C) and ensure the values from sections 2.1-2.6 are correct from slua903. Your discharge rate(C/10) seems to be ok. However, the charge rate appears a little slow. Your cell datasheet recommends standard charging at 0.2C and a cutoff at 0.01C.

Please watch this video to find more information about charging profiles for Lithium batteries: https://training.ti.com/introduction-li-ion-battery-charging.  For more information about charging your specific battery chemistry(LiFePO4) look at this website: https://www.power-sonic.com/blog/how-to-charge-lithium-iron-phosphate-lifepo4-batteries/ .

Sincerely,

Erik Cura

Hi Erik,

I have just started a new learning cycle. I will keep you updated of progress. Thanks for all your help and being so patient with me.

Bruce

Hello Bruce,

No problem. I hope it completes this time, if not we can examine the other solutions. 

Sincerely,

Erik Cura

Hi Erik,

Good news I seem to have managed to get all the way though a learning cycle. Bad news the version of bqStudion (1.3.101) does not seem to have the ability to create a 'Golden Image'.

Also once this is done how will I write it to the new chips when we start to manufacture battery packs.

Hopefully this is the last time I will be pretesting you.

Bruce