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BQ27426: The battery has not been removed after setting parameters.

Annie Liu
Genius 10295 points
Part Number: BQ27426
Other Parts Discussed in Thread: EV2400, BQSTUDIO,

Hi Team,

Software, tools: bqStudio (1.3.104 Build 1) + EV2400

BQ27426 is connected to the battery to be tested, and EV2400 is connected to the I2C interface of the 27426 device.

Set the parameters of BQ27426 in the software bqStudio, configure the chemical ID1202 matching the battery (4.2V), and lock the BQ27426 device with SEALED.

     

After completing the above steps, remove EV2400 from the set BQ27426 and set up other BQ27426 to be tested. During this period, the set fuel gauge is in an idle state with battery. 

When EV2400 was used again to connect the set BQ27426 to confirm the setting status, it was found that the set parameters of some devices were reset and restored to the device default parameters. 

Because the battery connected to the device is not removed during the idle period, a power-down reset is unlikely. Could you help analyze what other possibilities may cause BQ27426 to be reset by parameters when the power is not turned off after setting parameters?

Regards,

Annie

  • 0
    TI__Genius 17066 points

    Hello Annie, 

    On the gauges that were restored to the default parameters, was the ITPOR bit set? If this bit is set, then this could indicate that the gauge did either power cycle or reset. If this bit is not set on those devices, then it is possible that there was an issue when programming the parameters on those gauges. 

    Regards, 

    Jonny. 

  • 0 in reply to Robert
    TI__Genius 10295 points

    Hi Jonny,

    The ITPRO and WDRESET bits are both set to 1. The gauge is reset to default state.

    In the bqStudio software, Scan automatically refreshes on the Registers page. And Auto Refresh is also enabled on the DashBoard page. Is this situation related to the removal and reconnection of EV2400? Are there any other possibilities?

    Regards,

    Annie

  • 0 in reply to Annie Liu
    TI__Genius 17066 points

    Hello Annie, 

    Since the ITPOR bit was set, this tells me that the gauge was either power cycled or reset, either of these operations would cause the gauge to revert to the default data. This explains the behavior you are seeing. Please see the image below taken from the BQ27426 Technical Reference Manual. 

    Regards, 

    Jonny. 

  • 0 in reply to Robert
    TI__Genius 10295 points

    Hi Jonny,

    Setting the ITPOR bit 1 resets the device to default parameters. This is no problem. 

    The customer's question is that the SEALED is locked after the fuel gauge BQ27426 is set with relevant parameters. Generally understood, when the battery is not removed, the fuel gauge device should be able to maintain the set basic parameters for a long time, and update the relevant capacity and RA parameters through the charge and discharge process.

    Why are the parameters of the device reset when the customer does not operate the fuel gauge during the process after the device is locked? His sequence of operations is: Connect EV2400, set capacity/energy/taper current/cutoff voltage, set chemical ID, lock, remove EV2400, and then connect EV2400 after being idle for a period of time to confirm the setting of fuel gauge status. Is it because his sequence of operations wrong? Or is it caused by other unknown reasons?

  • 0 in reply to Annie Liu
    TI__Genius 17066 points

    Hello Annie, 

    I'm not sure If I fully understand your question, but I believe this is what I was trying to explain in my previous post. Whenever the gauge is power cycled or reset, the gauge reverts to the default values. When the gauge is power cycled or reset, the ITPOR bit gets set by the gauge. Since the ITPOR bit is set on the gauge, this tells us that at some point the gauge was power cycled or reset, thus causing the parameters the customer had set to return to the default values. Additionally, when you are writing the values to the gauge, please ensure that you send the SET_CFGUPDATE command. 

    Regards, 

    Jonny.