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BQ34110: Battery capacity estimation (FCC) value for Battery Low%

Axel V
Prodigy 110 points
Part Number: BQ34110

Hello,

For my application I use a Lead acid battery 12V, 38Ah. I use it as a UPS.

I need to estimate the total capacity of the battery regurlarly. For this, I perform a test where I discharge the battery.

From the technical reference manual, I know that I have to go below the EDV2 threshold. By default the RSOC of this threshold is Battery Low% = 7%. As my application is UPS it is not convenient to go that low in my remaining capacity (would be a problem if there's a power failure juste after the test). So I'd like to increase this threshold to something like 90% but I'm afraid that the estimation of the Full Charge Capacity will be too poor if I do so.

Is there any recommendation to define the battery low% parameter knowing that my desirata are a sufficiently well estimated total capacity and a Battery low% as high as possible ?

Thanks & Regards,

Axel

  • 0
    TI__Mastermind 25955 points
    Hi Axel,

    This isn't possible because the 7% EDV2 value is set to look for the ocv knee. As you near the 7% capacity of the battery, the slope increases significantly.

    The EDV value may be increased slightly, but you will need to graph the OCV of the cell vs SOC to determine the permissible percentage. The error will be too great where the slope approaches zero.

    Sincerely,
    Bryan Kahler