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BQ27510-G2: Cannot achieve full reset through RESET Control subcommand

Patricia DaSilva
Prodigy 80 points
Part Number: BQ27510-G2
Other Parts Discussed in Thread: BQEVSW, BQSTUDIO, BQ27510, EV2400, BQ27510EVM

I wish to conduct a full reset of my bq27510-G2. However, when I send the RESET subcommand (0x0041, preceded by the control command), I still have 0 in the low byte read from the RESET_DATA command (# of full resets) and a couple hundred in the high byte (# of partial resets). 

I believe I am in UNSEALED mode (when I read my control status bits I get 0 meaning neither FAS nor SS bits are set).

What else is missing to achieve a full reset?

  • 0
    TI__Guru 52115 points

    Hi Patricia,

    Which tool did you use toe send the RESET command?  Did you use bqEVSW? 

    Also,  I would suggest you upgrade the firmware to G3 firmware, which has several feature additions, performance improvements and better software support (e.g. bqStudio).

    Andy

  • 0 in reply to Andy Liu (BMS)
    Prodigy 80 points

    I just used my micro to communicate with the chip via I2C. Is there a way to use bqEVSW on chips that are already mounted to a pcb?  

  • 0 in reply to Patricia DaSilva
    TI__Guru 52115 points

    Yes. You should be able to communicate with the gauge device with bqEVSW and EV2300.

    Andy

  • 0 in reply to Andy Liu (BMS)
    Prodigy 80 points

    Sadly I don't have an EV2300. Without using anything but my micro communicating with the chip via i2c, is there a step I am missing to command a reset? Anything to look out for (e.g. is there a bit I can read that should be set when the chip receives the RESET?) ?

  • 0 in reply to Patricia DaSilva
    TI__Guru 52115 points

    Hi Patricia,

    Here is the sequence according to the BQ27510 TRM.

    To device address 0xAA, starting at command 0x00, write two bytes of data: 0x41 and 0x00.

    BQ27510 is a flash-based gauge device. Some configurations (e.g. chemistry id) must be done with bqStudio and EV2400 (or EV2300). They can never be accomplished using your microcontroller.   I believe you will need an EV2400 or EV2300 eventually. 

    Andy

  • 0 in reply to Andy Liu (BMS)
    Prodigy 80 points

    Hi Andy,

    Thank you for your help! Turns out we were overlooking the very important configuration and learning cycle steps. I now have an ev2400 and a bq27510EVM. I performed the Chem ID test selection process and matched to an ID of 1289 with a max deviation of 1.7%.

    However I am now struggling with the the first charge step in the learning cycle as the FC bit never sets. I have played with the Taper Current settings - first setting it to 200mA but the charge terminated around 268mA, so i increased my taper current to 280mA. I then repeated the whole process of discharging then recharging and the charge terminated again before setting FC - ending at an average current of about 368mA (see graphs below and screenshots of settings).

    Is there something I am missing?

    1) Does current calibration need to occur before learning cycle (there is a mismatch between what my power supply's measured current and that reported by the gauge when charging).

    2) does it seem to be a charger configuration issue? (We are using the LTC4162 charger (DC2038A eval board) with its default settings)

    3) Improperly set fuel gauge settings affecting charge termination or accurate detection of termination

  • 0 in reply to Patricia DaSilva
    TI__Mastermind 24870 points

    You need to taper longer. You are not tapering appropriately here. Make sure to refer to primary charge termination conditions in the TRM for more details on how the FC bit works.

  • 0 in reply to Kang Kang
    Prodigy 80 points

    May you be more specific about what is "appropriate tapering" ?

    Looking at the reference manual the only terms mentioned in relation to determining charge termination is "Charging Voltage", "Taper Current", and "Taper Voltage". Nothing specific on tapering.

  • 0 in reply to Patricia DaSilva
    TI__Mastermind 24870 points

    Hello,

    It is taper current and taper voltage. Those are the parameters you ahve to set for RSOC 100% and also FC bit setting.

  • 0 in reply to Kang Kang
    Prodigy 80 points

    As I myself mentioned in the reply above I am aware that these are the parameters I have to set; However, I am not aware how to set them "appropriately".

    I'm just trying to get clarity on what you meant earlier by "You are not tapering appropriately here" 

  • 0 in reply to Patricia DaSilva
    TI__Mastermind 24870 points

    Oh, set taper to the battery cell spec sheet.

    You want to typically taper at C by 10 or lower.

    Taper voltage needs to be set 100 mV from your CV voltage. If you CV at 4.35 V, you set this to 4.25 V.