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Gas Gauge chips in batteries

Teemu
Prodigy 150 points
Other Parts Discussed in Thread: BQ20Z90, BQ20Z955

Hi,

I'm trying to find a way to communicate with battery packs that have a TI Gas Gauge chip in them. Currently I'm testing two such batteries, originally from laptops. I've determined the SMBus lines to communicate with the chip, but I can only get the basic SMBus battery information in one, bit more in the second.

The first battery reads as "Device: 1, Ver:0.02" and only reads the Battery Status and Battery Mode values.

The second battery reads as "Device: 900, Ver:1.50" - bq20z90, but when I try to read the Data Flash values from the second battery, I get the error:

Error reading subClsld = 0 at block read cmd=120. Error Code = 6

Error reading Data Flash subclass Voltage, Code = 6

I know that these packs are both probably sealed, and it is not possible to modify or possibly get all the information without the full access to the pack, but I'm still wondering if it is possible to read values from Data Flash, even though there would not be possibility to change anything?

Thank you.

  • 0
    TI__Expert 3865 points

    You will still have access to the standard SBS functions per the Smart Battery Data Spec in the sealed mode. Extended SBS function and data flash are not accessible.

    If you have EV2300, the easiest way is to download the device EVSW from the product web page. Otherwise, you can follow the technical reference manual (also available in the product web page), Appendix A: Standard SBS commands, to get the battery information.

    It looks the device in the 1st battery pack is not communication. You may want to double check the hardware and the communication line.

  • 0 in reply to Jackie Hui
    Prodigy 150 points

    Thanks for the reply.

    However, now I have another model battery that I should use, but haven't been able to get it recognized by bqEASY. I have a sample control circuit where I can see the text printed in the chip and it reads bq 20z955 96TG4 ATQK. There is no chip stated as 20z955 in TI pages though.

    I did get a basic SMBus connection established with that also, but only for the basic battery status information without full chip recognition. Is this a valid TI chip, and is there a software/driver version somewhere available that could be used to communicate with the circuit?

    Thanks.

  • 0 in reply to Teemu
    TI__Intellectual 1430 points

    bq20z955 96TG4 ATQK contains custom firmware, you will only be able to get the basic battery information.  You need to contact the pack manufacture to know how to address addtional information if it is available.