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BQ27531-G1: Maximum Number of Parallel Lithium Ion cells

Jeffrey Dowell
Prodigy 70 points
Part Number: BQ27531-G1

Hello TI power management forum, 

I have a question about using the BQ27531-G1 gas gauge in concert with the BQ24192 single-cell battery charger with multiple Li-Ion batteries in parallel. Our product will use 18650 Li-Ion cells in a 1s5p configuration. The total capacity would be about 5x 3000mAh = 15Ah.

Have other customers had success with the gas gauge in a similar configuration? What is the upper limit to either the number of parallel cells or battery capacity for the gas gauging? 

Our concern is that the impedance tracking algorithm or coulomb counter might not be able to support so many parallel cells, since the batteries' internal resistances would be 1/5th of that for a single 18650 cell. We were wondering what the greatest number of cells the gas gauge was designed to support, or if other customers have had success with as many as five Li-Ion cells. 

Thanks for your help. 

Jeffrey Dowell

  • 0
    TI__Guru* 76230 points
    Hi Jeffrey

    You can scale the current and capacity values following the application note below:

    www.ti.com/.../slua760

    Our parametric search tool on ti.com lists the max capacity the gauge can support as 8000mAh. This is what limits or guides the no of cells in parallel that you can use. With the app note listed above, you should be able to go higher than 8Ah.

    thanks
    Onyx