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bq27441-g1

nelson chong1
Prodigy 105 points
Other Parts Discussed in Thread: BQ27441-G1, BQ27541

Hi, 

I am trying to implement the fuel gauging into our design, but I don't have much experience with fuel gauge chip. I have couple questions regarding BQ27441-G1. 

1. From my understanding BQ27441-G1 utilizes impedance tracking method for predicting the battery capacity, which means it has the advantages that device doesn't have to go to full discharge and charge cycle in order to get sort of accurate predicted capacity value. Instead, I need to run the charge and discharge cycle with a golden standard and create the golden image, then load the golden image too the rest of devices in production? As the user received the devices, and start to using the devices, the fuel gauging chip will update the information as the battery charge and recharge? 

2. I tried to update the chemistry ID using gauge studio, by selecting the chemID then click update chemistry, but the system always got stuck and kept going forever, crash. I turned off the load and the battery is not charging when I did that. The question is it suppose to take very long to update the chemistry ID? 

3. Reading the technical reference guide, it seems the chemID can only be read but not write through I2C? How do I configure ChemID? Is the ChemID part of the golden image information that get loaded onto the BQ27441? 

4. Our design has microcontroller communicate with BQ27441-G1 via I2C, is there anyway that this golden image could be loaded to the fuel gauge chip from the host microncotroller? Say if the user replace the rechargeable battery, mcu start up and pull BIN pin low to signal a battery instert to BQ27441-G1 chip. Then ideally, in the mcu firmware, we would need to reload the golden image to the fuel gauge chip?

Thanks,

Nelson

  • 0
    TI__Mastermind 24870 points

    Hello Nelson,

     

    1. Yes, as long as the gas gauge does not go through a POR, you should be okay to have the fuel gauge update the parameters as the user uses the battery.

     

    2. The bq27441-G1 will not allow chemistry updates, it will probably crash when you try to update the chemistry.

     

    3. You will not be able to configure the chemID. This is a bq274xx series gas gauge. If you want to configure the chemID, please consider using a bq275xx series gas gauge.

     

    4. Yes, the golden image can be loaded via a sequence of I2C commands which is generated via the "golden image" plug-in of gaugestudio.

     

    Thanks,

    Kang Kang

  • 0 in reply to Kang Kang
    Prodigy 105 points

    HI Kang,

    Can I still write the overwrite the design capacity? I was following the pseudo code example and trying to update the Design Capacity, but was having some issue. I could read all the datablock, but when I tried to write to Design Capacity, it doesn't let me update it.  Is there a way I could contact you directly by phone or email so that I could and ask you a few quick questions.

    Thanks,

    Nelson

  • 0 in reply to Kang Kang
    Prodigy 105 points

    Hi Kang,

    With the current default chemID 0x0128 for the BQ27441, I can't change the chemID to 0x0100. But If I need something working as prototype yet just want to get the approximate capacity for now, can I just change the Design Capacity so that the SOC and Remaining capacity will be 2500 mAh instead of the currently 1340 mAh. I saw in teh data memory summary, where the Design Capaciy is deault to 1340 for -G1A, but max value allowable is 32767.

    Does all the 275xx chemID is configurable? What about BQ27541?

    Thanks,

    Nelson

  • 0 in reply to nelson chong1
    TI__Genius 14985 points

    Hi Nelson,

    The bq27441 Quick Start Guide gives you an overview of how to use this gauge including some flow charts you can implement in code.

    We also have a Linux driver which you can leverage:

    http://processors.wiki.ti.com/index.php?title=Linux/Android_Software_Solutions_for_TI_Single-cell_Gas_Gauges

    You cannot change the chemID used in the bq274xx gauges.  They are ROM gauges.

    The bq275xx and bq2774x gauges are flash-based and you can change the chemID.

  • 0 in reply to dMax
    Prodigy 105 points

    Hi Kang,

    According to the SLUUAC9 page 25, DataMemory Subclass ID82 offset 10 Design Capacity is default to A = 1340. But the max value is 32767. However, when I tried to use the extended commands in page 20 to write the Design Capacity(), then I found out that the table 5-1 says Design Capacity is Read only??? That means the BQ27441-G1A is only for gerenic LiCoO2 battery chemistry with the default Design Capacity 1340mAh?

    Thanks,

    Nelson

  • 0 in reply to nelson chong1
    Prodigy 105 points

    Hi Kang, 

    Thanks for your help, I really appreciate your quick response. I was wondering if you have an email address I could chat with you directly? I just have a few more questions need to clear up. It will be very helpful if you could do that. 

    Thanks, 

    Nelson

  • 0 in reply to nelson chong1
    TI__Mastermind 24870 points

    Hello Nelson,

    I have sent you a friend request and we can do a private chat where I can provide you with my email address.

    Thanks,

    Kang Kang