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Original question:

BQ76940: Schematic and PCB review

BQ76940: VCT not triggering

Noel Binny Abraham
Intellectual 580 points

Part Number: BQ76940
Other Parts Discussed in Thread: BQ78350-R1A, BQ78350, BQSTUDIO

Tool/software:

Hi Luis,

Hope you been doing good!

We were testing the BMS for a 13S configuration and have observed that the VCT is not being hit eventhough all the conditions are being satisfied.
I have the log files and .gg files for this ready with me that i have shared on your private chat. Do go through it and let me know if im doing something wrong.

Best Regards,
Noel Binny Abraham

  • 0
    TI__Mastermind 31845 points

    Hi Noel,

    This sounds like a gauge question, what gauge are you using?

    Regards,

    Diego

  • 0 in reply to Diego
    Intellectual 365 points

    Hi Diego,

    I'm working with Noel. We are using BQ78350-R1A. The thread was meant to be for the BQ78350, but we mistakenly put the incorrect part number.

  • 0 in reply to Diego
    Intellectual 580 points

    Hi Diego,

    We are using BQ78350-R1A
    I can share you the .gg and log files on pvt chat. Please do look into it and let me know what might be the problem.

    There's one more problem that we've faced during testing. We removed the temp sensors while charging was active, the guage read -52 deg.C, UTC bit was set to high as shown on BQSTUDIO, and all the conditions for fet turn-off was achieved under UTC, but the charging never got suspended. The SU bit was also toggled to high, but no change was observed with the CHG and DSG bits. Charging continued and this is not what we were expecting. You will get a better idea when you look at the .gg and log files when this scenario was tested. 

    Do look into these and let me know what we are doing wrong.

    Best Regards,
    Noel

  • 0 in reply to Noel Binny Abraham
    Intellectual 580 points

    Hi Diego,

    Please look into this and let me know.

  • 0 in reply to Noel Binny Abraham
    TI__Mastermind 31845 points

    Hi Noel,

    Sorry for the delay, Please share the log and configuration.

    If you have one of the VCT and one of the UTC,  please label the logs accordingly.

    Regards,

    Diego

  • 0 in reply to Diego
    Intellectual 580 points

    Hi Diego,

    I've attached the gg and the VCT file on this thread ( e2e.ti.com/.../bq78350-r1a-vct-not-triggering ). Please download the files from here.

    I have one log file for UTD. Same behaviour is observed during both UTC and UTD. If you would still need a UTC log as well, do let me know

    Fullscreen BQ76940 13S_DSG test 4_UTD.log Download 
    Thu Dec 19 12:28:47 IST 2024

Device Version Info = 1e9b_3_00
BQZ Device Name = bq78350R3
BQZ Firmware Version = V3_00_BLD31

Design Capacity = 6300
Design Voltage = 3700
Specification Info = 0x1031
Manufacturer Date = 2024-11-7
Serial Number = 0x0002
Manufacturer Name = Revogreen Tech
Device Name = RT501
Device Chemistry = LION

Sample,DateTime,ElapsedTime,ManufAccess,RemCapAlarm,RemTimeAlarm,BattMode,@Rate(@),@TimeFull,@TimeEmpty,@RateOK,Temperature,Voltage,Current,AvgCurr,MaxErr,RSOC,ASOC,RemCap,FullChgCap,RunTimeEmty,RunTimeEmty,AvgTimeFull,ChgCurr,ChgVolt,BattStat,CycleCnt,PendingEdv,SoH,OpStatA,OpStatB,TempRange,ChgStat,GaugeStat,MfgStat,SafetyAlertAB,SafetyStatAB,SafetyAlertCD,SafetyStatCD,PFAlertAB,PFStatAB,PFStatAB,CellVolt1,CellVolt2,CellVolt3,CellVolt4,CellVolt5,CellVolt6,CellVolt7,CellVolt8,CellVolt9,CellVolt10,CellVolt11,CellVolt12,CellVolt13,CellVolt14,CellVolt15,ExtAvgCellVolt,TS1 Temp,TS2 Temp,TS3 Temp,CellTemp,FetTemp,GaugeInternalTemp,LogRowTime(ms),LogStatus
1,2024-12-19 12:28:51,4.016,0x0709,300,10,0x6001,0,65535,65535,1,-52.1,53932,-455,-435,8,98,94,5904,6044,780,812,65535,0,0,0x00C0,2,3423,96,0x0907,0x0000,0x01,0x14,0x8040,0x0230,0x0000,0x0800,0x0000,0x0000,0x0000,0x0000,0x0000,4069,4156,4160,4157,4160,4159,4159,4159,4155,4160,4158,4158,4122,0,0,0,-52.7,-52.9,-52.1,-52.1,-273.2,34.3,954,SUCCESS
2,2024-12-19 12:28:55,8.028,0x0709,300,10,0x6001,0,65535,65535,1,-52.1,53929,-454,-441,8,98,94,5903,6044,780,803,65535,0,0,0x00C0,2,3423,96,0x0907,0x0000,0x01,0x14,0x8040,0x0230,0x0000,0x0800,0x0000,0x0000,0x0000,0x0000,0x0000,4069,4155,4160,4157,4160,4158,4159,4159,4155,4159,4158,4157,4122,0,0,0,-52.8,-52.9,-52.1,-52.1,-273.2,34.3,941,SUCCESS
3,2024-12-19 12:28:59,12.035,0x0709,300,10,0x6001,0,65535,65535,1,-52.1,53927,-454,-444,8,98,94,5903,6044,780,798,65535,0,0,0x00C0,2,3423,96,0x0907,0x0000,0x01,0x14,0x8040,0x0230,0x0000,0x0800,0x0000,0x0000,0x0000,0x0000,0x0000,4069,4155,4160,4157,4160,4158,4158,4158,4155,4159,4158,4158,4122,0,0,0,-52.8,-52.9,-52.1,-52.1,-273.2,34.3,951,SUCCESS
4,2024-12-19 12:29:03,16.036,0x0709,300,10,0x6001,0,65535,65535,1,-52.1,53925,-455,-447,8,98,94,5902,6044,778,792,65535,0,0,0x00C0,2,3423,96,0x0907,0x0000,0x01,0x14,0x8040,0x0230,0x0000,0x0800,0x0000,0x0000,0x0000,0x0000,0x0000,4069,4155,4160,4156,4160,4158,4158,4158,4155,4158,4157,4157,4122,0,0,0,-52.8,-52.9,-52.1,-52.1,-273.2,34.3,979,SUCCESS


    Thanks and Regards,
    Noel Binny Abraham

  • 0 in reply to Noel Binny Abraham
    TI__Mastermind 31845 points

    Hi Noel,

    Why is the temperature reported to be -52.1? is this accurate?

    Additionally, the current reading is negative so the chg bit will not set.

    Regards,

    Diego

  • 0 in reply to Diego
    Intellectual 365 points

    Hi Diego,

    We're trying to simulate a condition where the gauge will go into the UTD/UTC condition by removing the thermistors.


    Diego said:
    Additionally, the current reading is negative so the chg bit will not set


    The log which is attached to this thread is for the problem with UTD. The discharge does not stop even after the UTD bit gets set. On the same note, the XDSG bit also remains at 0 when the UTD bit gets set.

    I am attaching the log files again and labelling them accordingly to avoid any further confusion.

    UTD Log: 

    Fullscreen 0045.BQ76940 13S_DSG test 4_UTD.log Download 
    Thu Dec 19 12:28:47 IST 2024

Device Version Info = 1e9b_3_00
BQZ Device Name = bq78350R3
BQZ Firmware Version = V3_00_BLD31

Design Capacity = 6300
Design Voltage = 3700
Specification Info = 0x1031
Manufacturer Date = 2024-11-7
Serial Number = 0x0002
Manufacturer Name = Revogreen Tech
Device Name = RT501
Device Chemistry = LION

Sample,DateTime,ElapsedTime,ManufAccess,RemCapAlarm,RemTimeAlarm,BattMode,@Rate(@),@TimeFull,@TimeEmpty,@RateOK,Temperature,Voltage,Current,AvgCurr,MaxErr,RSOC,ASOC,RemCap,FullChgCap,RunTimeEmty,RunTimeEmty,AvgTimeFull,ChgCurr,ChgVolt,BattStat,CycleCnt,PendingEdv,SoH,OpStatA,OpStatB,TempRange,ChgStat,GaugeStat,MfgStat,SafetyAlertAB,SafetyStatAB,SafetyAlertCD,SafetyStatCD,PFAlertAB,PFStatAB,PFStatAB,CellVolt1,CellVolt2,CellVolt3,CellVolt4,CellVolt5,CellVolt6,CellVolt7,CellVolt8,CellVolt9,CellVolt10,CellVolt11,CellVolt12,CellVolt13,CellVolt14,CellVolt15,ExtAvgCellVolt,TS1 Temp,TS2 Temp,TS3 Temp,CellTemp,FetTemp,GaugeInternalTemp,LogRowTime(ms),LogStatus
1,2024-12-19 12:28:51,4.016,0x0709,300,10,0x6001,0,65535,65535,1,-52.1,53932,-455,-435,8,98,94,5904,6044,780,812,65535,0,0,0x00C0,2,3423,96,0x0907,0x0000,0x01,0x14,0x8040,0x0230,0x0000,0x0800,0x0000,0x0000,0x0000,0x0000,0x0000,4069,4156,4160,4157,4160,4159,4159,4159,4155,4160,4158,4158,4122,0,0,0,-52.7,-52.9,-52.1,-52.1,-273.2,34.3,954,SUCCESS
2,2024-12-19 12:28:55,8.028,0x0709,300,10,0x6001,0,65535,65535,1,-52.1,53929,-454,-441,8,98,94,5903,6044,780,803,65535,0,0,0x00C0,2,3423,96,0x0907,0x0000,0x01,0x14,0x8040,0x0230,0x0000,0x0800,0x0000,0x0000,0x0000,0x0000,0x0000,4069,4155,4160,4157,4160,4158,4159,4159,4155,4159,4158,4157,4122,0,0,0,-52.8,-52.9,-52.1,-52.1,-273.2,34.3,941,SUCCESS
3,2024-12-19 12:28:59,12.035,0x0709,300,10,0x6001,0,65535,65535,1,-52.1,53927,-454,-444,8,98,94,5903,6044,780,798,65535,0,0,0x00C0,2,3423,96,0x0907,0x0000,0x01,0x14,0x8040,0x0230,0x0000,0x0800,0x0000,0x0000,0x0000,0x0000,0x0000,4069,4155,4160,4157,4160,4158,4158,4158,4155,4159,4158,4158,4122,0,0,0,-52.8,-52.9,-52.1,-52.1,-273.2,34.3,951,SUCCESS
4,2024-12-19 12:29:03,16.036,0x0709,300,10,0x6001,0,65535,65535,1,-52.1,53925,-455,-447,8,98,94,5902,6044,778,792,65535,0,0,0x00C0,2,3423,96,0x0907,0x0000,0x01,0x14,0x8040,0x0230,0x0000,0x0800,0x0000,0x0000,0x0000,0x0000,0x0000,4069,4155,4160,4156,4160,4158,4158,4158,4155,4158,4157,4157,4122,0,0,0,-52.8,-52.9,-52.1,-52.1,-273.2,34.3,979,SUCCESS


    VCT Log: 0045.RT501_003_chg test 3 continued 2.log


    GG file: 5344.13S_V1_3.gg.csv

  • 0 in reply to Bhavil Nagar
    TI__Mastermind 31845 points

    Hi,

    Understood, under temperature condition does not open FETs.

    undertemp.pdf

    Regards,

    Diego

  • 0 in reply to Diego
    Intellectual 365 points
    Diego said:
    under temperature condition does not open FETs.

    But if the UTD bit is set, then the gauge should terminate discharge by setting the XDSG bit to 1(as stated in the TRM), which is not happening in our case.




  • 0 in reply to Bhavil Nagar
    TI__Mastermind 31845 points

    Hi,

    I understand the issue, can you log a temperature change crossing the threshold and see if that triggers the proper bits to flip.

    Regards,

    Diego