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bq40z50 can't charge

Phien Nguyen Thanh22
Intellectual 570 points
Other Parts Discussed in Thread: BQ40Z50, BQ24735, BQSTUDIO, EV2400

Hi all,

I am facing a problem that can't charge  2-Series Li-on battery with bq40z50 and bq24735.

In 0x16 BatteryStatus():  error code is UnknownError. OperationStatus()[XCHG] = 1 and OperationStatus()[XDCHG] = 1. So, I found in 4.12 Charge Disable and Discharge Disable section but I can't find any conditions that the device can disable charging. These are value of some registers:

+ 0x0054 OperationStatus: 0x6921 (charge and discharge: disable - SAFETY mode status: active - SECURITY mode: full access - System present low: active)

+ 0x0055 ChargingStatus: 0x0402

+ PF alert: 0x00

+ PF status: 0x00

+ Safety alert: 0x00

+ Safety status: 0x08000000 (Undertemperature During Discharge: detected)

+ 0x16 BatteryStatus():  0x00C7 (Error Code: UnknownError)

Thanks for any help.

Phien

PS: This is technical ref of bq40z50 that i used: www.ti.com/.../sluua43a.pdf

  • 0
    TI__Expert 3385 points
    Hi Phien,

    Can you please attach an SREC for the device you have described above? You can obtain this in bqstudio under the "Firmware" tab.

    Best,
    Justin
  • 0 in reply to Justin Erfan
    Intellectual 570 points

    Hi Justin,

    I can't send you SREC file because this is my designed board, and i don't have usb-based PC interface board. Do you need more info about my bq40z50 ? 

    And can you give me some advice when facing this problem ?

    Thank you very much,

    Phien Nguyen

  • 0 in reply to Justin Erfan
    Intellectual 570 points

    Hi Justin,

    After changing configuration, safety status = 0x00. But Charge and Discharge are still disable. Now, Operation status value: 0x61A1 (FUSE: active, Battery Trip Point Interrupt: 1) and Battery status: 0x03D7. Are something wrong with these registers ?

    I am doubting about temperature sensor in the bq40z50: temperature of TS1 -> TS4 in DA2 are approximately 0x1255 (190 Celsius Degree, but internal temperature is OK), although i disable temperature sensor (by SMBus command and connected these pins to gnd)but when i change temperature threshold (T1 -> T5) the ChargingStatus change the temperature region of cell battery.

    Thank you very much,
    Phien Nguyen

  • 0 in reply to Phien Nguyen Thanh22
    TI__Expert 3385 points

    Hi Phien,

    The fuse bit being set will prevent you from charging. Is your fuse pin on the device floating?

    Best,
    Justin

  • 0 in reply to Justin Erfan
    Intellectual 570 points

    Hi Justin,

    Fuse pin is floating, now. I try connecting it to gnd (without resister) and fuse status is inactive. But it is still not charging. In the registers, i think the status is ok: safety status, safety alert, PF alert, PF status is 0x00, except for operation: 0x6181 (Battery Trip Point Interrupt: 1), Battery status: 0x03D7 (unknown error), GaugingStatus: 0x04D5 (MaxError() > Max Error Limit, OCV Reading Not Taken or Not in RELAX)

    Thank you very much,

    Phien Nguyen

  • 0 in reply to Phien Nguyen Thanh22
    TI__Expert 3385 points

    Hi Phien,

    Yes, if you are not using the fuse, this pin should be tied low. It seems that your battery is fully discharged. 

    Your OperationStatus of x6181 shows that XCHG and XDSG are set, so your charging and discharging are disabled.

    Are your FETs enabled?

    Can you please send the contents of ManufacturingStatus ?

    Best,

    Justin

  • 0 in reply to Justin Erfan
    Intellectual 570 points
    Hi Justin,

    My battery is fully discharge. FET_EN is Enable (Bit 4 of ManufacturingStatus). Now, I am at home, so i will send you the contents of ManufacturingStatus tomorrow ?

    Thank you very much,
    Phien Nguyen
  • 0 in reply to Justin Erfan
    Intellectual 570 points

    Hi Justin,

    The ManufacturingStatus is 0x0010. Now I change the battery with voltage is 4.1V. Other registers:

    + Operation staus: 0x6901 >> charge, discharge are disable, SAFETY mode status active.

    + Charge status: 0x0402

    + Gauging status: 0x04D0

    + Battery status: 0x00C7 (unknown error)

    (Before i disable Protections A, B, C, D now i enable them)

    Thank you very much,

    Phien Nguyen

  • 0 in reply to Phien Nguyen Thanh22
    Intellectual 570 points

    Hi Justin,

    I send you my schematic of bq40z50. BAT+ is connected to Phase of bq24735 (I config it 8.4V output).

    Some feature be changed in the schematic:

    + PRESS connect to gnd.

    + Fuse  connect to gnd

    + MOSFET Q21 pin 2 to BAT+, pin 3 to R388

    Thank you very much,

    Phien Nguyen

  • 0 in reply to Phien Nguyen Thanh22
    TI__Expert 3385 points
    Hi Phien,

    Do you still see Safety status: 0x08000000 (Undertemperature During Discharge: detected)

    Your SS bit may be set because of one of the safety statuses being set, thus not letting you charge/discharge

    Can you use an EV2400 to create a log and send us an SREC? If not, can you send me the Temperature Enable and Temperature Mode contents
  • 0 in reply to Justin Erfan
    Intellectual 570 points

    Hi Justin,

    These are my registers value:

    The ManufacturingStatus is 0x0010. ( battery with voltage is 4.1V). Other registers:

    + Operation staus: 0x6901 >> charge, discharge are disable, SAFETY mode status active.

    + Charge status: 0x0402

    + Gauging status: 0x04D0

    + Battery status: 0x00C7 (unknown error)

    + Safety status, Safety alert, PF status, PF alert = 0. >> I don't understand this, status look OK but SS bit = 1, and charge and discharge are disable.

    Are there any reasons that SS bit = 1, but status are OK ? And i didn't calibrate voltage, temperature ...

    Thank you very much,

    Phien

  • 0 in reply to Phien Nguyen Thanh22
    TI__Expert 3385 points

    Hi Phien,

    Also one other thing to note is that your gauging status you are reporting is 2 bytes long, but this register only holds 1 byte. I am wondering if you are having communication errors. Can you try to use an ev2400 with bqStudio to retrieve the data, capture a log and SREC. This will help debugging.

    Best,
    Justin