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Original question:

BQ76920: Need information regarding BQ76920

BQ76920: Need information regarding BQ76920

Reena Patel
Intellectual 375 points
Part Number: BQ76920
Other Parts Discussed in Thread: BQ78350, BQSTUDIO, BQ78350-R1

Hello sir,

Thanks for your Response,

This solve my query. But i want to know can i connect BQ76920 chip-set directly with my host microcontroller. And if yes, Am i able to read Battery percentage through I2C communication.

And if not, Why do i need Fuel gauge(BQ78350) with my chip-set for battery monitoring. And in that which step i need to do with fuel gauge. Because i did not find learning cycle option in BQSTUDIO. 

Thanks & your best Regards,

Reena Patel

  • 0
    TI__Guru* 81034 points
    Hi Reena,

    You can use the BQ76920 directly with a host microcontroller. However, the BQ76920 does not report SOC so you would need to write code for the microcontroller to determine the SOC using the information reported by the BQ76920 (voltage, temperature, and coulomb counting). For lower accuracy this code may be simple, but to achieve high accuracy on the SOC it can be very complex. Here is a short video that give a basic overview of battery gauging: training.ti.com/what-gauge-and-why-do-you-need-it

    The BQ78350 is a companion gauge designed to work with the BQ769x0 family. It is highly configurable but does not require the user to write any software. This is easier for the user, but might offer less flexibility since the software algorithm cannot be modified. The basic guide for configuring the BQ78350-R1 is here: www.ti.com/.../slua924.pdf The BQ78350-R1 uses a CEDV gauging algorithm. Section 2.3 goes through the steps you need to follow to set up the gauging feature.

    Best regards,
    Matt
  • 0 in reply to Matt Sunna
    Intellectual 375 points
    Hello sir,
    Thanks for your reply,
    We decide to go with only Battery Monitoring device only. I have hardware. i have checked voltage through I2C communication also. Now i want SOC . But do not know how can i calculate SOC from voltage. is there any algorithm ?
    Please help me out for that.

    Regards & Thanks,
    Reena Patel
  • 0 in reply to Reena Patel
    TI__Guru* 81034 points
    Hi Reena,

    Multiple algorithms exist for determining SOC with different levels of accuracy. I cannot share details on the algorithms used on TI battery gauges since they are proprietary, but I can point you to good link for getting started: e2e.ti.com/.../video-battery-management-university-fuel-gauging-101

    If you have good characterization data for your battery (voltage vs. SOC curve), you can make an accurate SOC determination from voltage alone. However, the voltage reading is also affected by the current load and temperature. The BQ76920 monitor also reports current (coulomb counting) and temperature, so this information can also be used in the SOC calculation. You will need to characterize your battery over different temperatures and current loads to understand how this impacts the observed voltage. One more thing to consider is that the battery capacity does decrease over time as the battery ages.

    Best regards,
    Matt