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BQ27532-G1: Enabling support for BQ fule guage

Iztok Blazinsek92
Prodigy 40 points
Part Number: BQ27532-G1
Other Parts Discussed in Thread: BQSTUDIO

Hello,

we have a device with BQ27532 fuel gauge and must support two different batteries:
first is LP7245125-5000 and the second is LP602248-650 (both lithium polymer).

We would like to know:
1) which chemistry to use (the supplier of BQ recommended to ask this directly here here)?
We preformed multiple measurements and uploaded data to your web page as per documentation (SLVA725), but the returned ID(-s) varies...

2) when setting the chemistry - is this one parameter or a set of parameters? Can this be done within embedded application or only by use of the BQ tool?
Do we need different chemistry IDs for those two batteries?

3) golden file - both of our batteries uses the same pack, but different capacity. Is there a way to have one golden file for both batteries?
From documentation i can see this file can be uploaded with embedded application?

Thank you for your help.

Best regards. I





  • 0
    TI__Expert 3995 points

    Hi,

    1) Please use the GPS tool report for battery chemistry match with the lowest deviation as shown in photos attached.

    2) Chemistry ID is a set of parameters and can only be selected and uploaded to the gauge via bqStudio SW, also there should be a specific chemistry ID for each battery.   

    3) You should create a golden image for each battery. It worth mentioning that you need to run a learning cycle for each of your batteries before creating the golden image, the purpose of the learning cycle is to allow the gauge to learn the battery capacity and impedance for accurate battery gauging. please refer to the attached document for achieving a successful learning cycle.1185.slua597.pdf

    Best regards,

    Haidar 

  • 0 in reply to Haidar Hamoo
    Prodigy 40 points
    Thank you for your quick response.

    We already executed the measurements, needed for chemistry ID selection 4 times. Only in two cases, we get the same chemistry ID suggested by the GCP. The results are as follows:

    1)
    Chem ID max DOD error, % Max R deviation, ratio
    Best chemical ID : 3164 Best chemical ID max. deviation, % : 2.6
    Summary of all IDs with max. DOD deviation below 3%

    Chem ID max DOD error, % Max R deviation, ratio
    3164 2.6 0.3
    455 2.89 0.22

    2)
    Best chemical ID : 1305 Best chemical ID max. deviation, % : 3.82
    Summary of all IDs with max. DOD deviation below 3%

    Chem ID max DOD error, % Max R deviation, ratio
    0 0 0

    3)
    Best chemical ID : 2033 Best chemical ID max. deviation, % : 2.72
    Summary of all IDs with max. DOD deviation below 3%

    Chem ID max DOD error, % Max R deviation, ratio
    2033 2.72 0.28

    4)
    Best chemical ID : 1305 Best chemical ID max. deviation, % : 2.38
    Summary of all IDs with max. DOD deviation below 3%

    Chem ID max DOD error, % Max R deviation, ratio
    1305 2.38 0.45
    2073 2.79 0.55
    2033 2.99 0.47

    Is ti normal, to get this much of a spread?
    The only ID, seen twice, is 1305 . Should we take this one for this particular battery?
    The measurements were done with the use of thew BQ GDK at room temperature in your lab.

    However the battery was not in the temperature stable enviroment (we did not put it at the time into the temperature chamber). Can the temperature deviations be the cause of this inconsistent results?

    Again, thank you for your excellent assistance.

    Best regards, I
  • 0 in reply to Iztok Blazinsek92
    TI__Expert 3995 points

    Hi,

    The results you got as a match ChemID for your battery are ok but you can get better results if you follow the recommendation for finding ChemID in the link below:

    Please make sure to charge the battery at C/2 rate to the Max. charging voltage of the battery (you can find it in Battery datasheet), then discharge at a rate between C/5 - C/10 to a terminate voltage of 2.8V - 2.9V to get the battery voltage profile so the tool can find a close match. Battery temperature during chg/dish can affect the results if there was a significant temperature variation and it is recommended but not required to attach external temperature sensor on the battery while longing data to be submitted to CHEMGPC tool.

    As for the spread results, the tool will try to find the closest match to your battery voltage profile and not the exact match and that's why you may see some deviation in the results. An exact match to your battery can be found if you send us your battery and we can characterize it in our labs to give you exact ChemID but this process requires 3-4 weeks after we receive the battery. 

    Regards,

    Haidar

  • 0 in reply to Haidar Hamoo
    Prodigy 40 points
    Dear Haidar,

    thank you for the information provided.

    We will try to measure the data required for chemistry ID selection in temperature stable environment with the settings you provided. I have two additional questions:

    1) We need to configure (program) the fuel gauges chips before use. What is the best way to integrate this procedure in production process? Is there a command/script interface which we can use to load Chem ID and golden file to the BQ chip?

    2) Is there no way to upload the Chemistry ID (and golden file data) with embedded application? The battery in our product can be changed after the product is deployed (or when the battery is pass its lifetime).

    Again, thank you for your help.

    Best regards, I
  • 0 in reply to Iztok Blazinsek92
    TI__Expert 3995 points

    Hi, 

    1) You can program the gauge using your system MCU with FlashStream as explained in the document attached below section 3.2.1;

    2)  You can created a DFFS file (Golden Image) and have it stored in your system non-volatile memory and then have it written to the gauge after a battery swap is done.

    Thank you for choosing TI devices in your design and please do nnot hestitate to post any question or questions you may still have.

    Best regards,

    Haidar 

  • 0 in reply to Haidar Hamoo
    Prodigy 40 points
    I can't download the attached document.
    Can you please re-attach it?

    Thanks.

    Best regards, Iztok
  • 0 in reply to Iztok Blazinsek92
    TI__Expert 3995 points

    Hi Iztok,

    please find the link attached:

    Best regards,

    Haidar