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BQ27411-G1: SoC and SoH reads zero

Swetha Shri Na
Prodigy 20 points
Part Number: BQ27411-G1
Other Parts Discussed in Thread: EV2400, GPCCHEM, BQEVSW, BQSTUDIO

Hello,

I am working at Tismo Technology Solutions (https://www.tismotech.com). We are developing a product for our client, the BQ27411DRZT-G1A IC plays a very major part in that product.

 BQ27411DRZT-G1A IC is used to compute the battery related parameters. I am able to read the device ID(0x0421), Chem ID(0x0128) (using I2C communication), the value of those parameters were same as mentioned in the datasheet. The voltage of the battery reported by the BQ27411-G1 IC was correct and got verified externally. The SOC and SOH (all the battery related parameters) were reported as zero. 

To get the correct values for SOC and SOH the chem ID of the battery that I am using should be set. How can I check the chem ID of the battery that I am currently using? Also how can I set the chem ID via I2C commands(Because I don't have EV2400 module)? 

I need to compute design capacity, design energy, terminate voltage, and taper rate. How to compute these parameters? Is there any tool available for that? How can I write these four parameters to the IC. Are the steps mentioned in the "Quick start guide of  BQ27411DRZT-G1A IC" suffice to get the IC working?

The next topic is regarding the I2C communication. 

I have configured the I2C clock speed of the master  to 400kHz, hence I went with the below implementation (I2C command waiting time for F <= 400kHz). I was not able to read the appropriate device ID and chem ID.

 

 

But, I was able to read the appropriate device ID and chem ID by following the below implementation(I2C command waiting time for F <= 100kHz).

 

Any thoughts on why I2C command waiting time made a difference?

 

Thanks in advance,

Swetha.

  • 0
    TI__Guru 57697 points

    Hello Swetha,

    1. You can use the GPCCHEM tool to get the correct Chem ID

    2. For 400KHz I2C communication the capacitance on the bus must be low. Check if the waveforms are sharp, otherwise you may need to modify your board design or use lower speed.

  • 0 in reply to Shirish
    TI__Guru** 103125 points

    Hello Swetha,

    Just to add on to what Shirish has already mentioned:

    The BQ27411 is a ROM based gauge, this means upon POR the default values stored will be populated into the RAM again and anything modified will be cleared, including the chem ID.

    If you want to modify the preloaded chem ID, you will need an EV2400 to export the golden flash stream file that would contain on your configuration changes. The chem ID data is proprietary so there is no way to get the single golden image without it. After you have the flash stream you can use the app note SLUA801 and your own MCU to program.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Shirish
    Prodigy 20 points

    Thanks for the reply Shirish.

    Regarding the I2C communication, the waveforms are sharper. Shall I proceed with command waiting time sequence ( F <= 100kHz) for the 400kHz I2C communication(Master)?

    Thanks,

    Swetha.

  • 0 in reply to Wyatt Keller
    Prodigy 20 points

    Thanks for the reply Wyatt Keller.

    We are using the battery of following specification : Lithium polymer,3.7V  4000 mAh. Is the Chem ID for this battery type predefined? 

    We currently have the EV2300 module (EV2300 is compact with windows 7 PC right?). Can EV2300 be used with BQ27411 fuel gauge IC ?(Tapping the I2C lines from the IC to the module directly). Or EV2300 can be used only with BQ27411 EVM module?

    Thanks,

    Swetha.  

  • 0 in reply to Swetha Shri Na
    TI__Guru 57697 points

    Hello Swetha,

    The capture above is a digital capture which does not show the actual waveform. You will need an oscilloscope. It is perfectly ok to use the waiting time sequence of F<=100KHz if that resolves your problem.

  • 0 in reply to Swetha Shri Na
    TI__Guru 57697 points

    The specific battery manufacturer/model is associated with a given chem ID. Sending the logs to the GPCCHEM tool will let you know whether the specific battery chemistry is acceptable for bq27411

  • 0 in reply to Swetha Shri Na
    TI__Guru 57697 points

    EV2300 is recognized and supported by bqEVSW and bqStudio software. The EV2300 driver may not always work on 64 bit Windows. If Windows can recognize the EV2300, then EV2300 will work fine with all BQ gauges.