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bq27510-g3 Design Capacity at 4,1V

Pierre Le Gargasson
Intellectual 260 points
Other Parts Discussed in Thread: BQ27510-G3

Hi everybody,

I use 9600 mAh pack charged at 4,1V with bq27510-g3. I get a golden image with learning cycle at 4,2V and a second at 4,1V. This worked fine until SOH and TTE dramatically decrease.

According to this post step 6, I made a mistake with SOH Load I, left by default.

My question : for the end product, charging at 4,1V, should I set Design Capacity at 9600 mAh (used for learning cycle at 4,2V) or 8640 mAh (90%) to have SOH = 100% ?

Regards, Pierre

  • 0
    TI__Mastermind 24870 points

    Hello Pierre,

    SOH is calculated as predicted FCC(25C, SOH LoadI) over the Design Capacity.

    My assumption is that your FCC at 25C is reporting 8640 mAh and you've set design capacity equal to 9600 mAh. Is this correct?

    Do you have a log file of the cycle? It would help us analyze the different reasons on why the TTE or SOH dropping dramatically.

    Thanks,

    Kang Kang

  • 0 in reply to Kang Kang
    Intellectual 260 points

    Hello Kang,

    Your assumption is correct.

    You will find attached files of :

    1 - charge and discharge logs at cycle count = 1

    2 - screenshot of RAM at cycle count = 13 => SOH starts to decrease. After 18 cycles counts, one product SOH = 39% and TTE at full charge is divided by 2. To retrieve 100% of autonomy, I have to force a discharge until 3V or unplug pack. In my final application, I use TTE to stop the product.

    3 - Golden Image

    From now, I test the same Golden Image with Design Capacity = 8640 mAh and SOH Load I = -1200 mA.

    Thanks for your help. Regards, Pierre.logs.zip