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BQ27542-G1: BQ27542-G1

Joachim Pingel
Prodigy 20 points
Part Number: BQ27542-G1

I have a problem regarding the calculation of SOH. As described in the datasheet, the SOH is calculated by SOH=FCC/Design-Capacity. 

Due to the requirements in our application, we set the "Terminate Voltage" to 3450mV to get SOC=0% if that voltage is reached.

By now, the BQ27542-G1 will calculate the SOC 0 to 100% correctly within our system-limits but due to the higer terminate-voltage the FCC (after sucessfull learning-cycle) is calculated to about 2300mAh with a "Design Capacity" for the cell of 3000mAh. The result of this is, that the SOH is calculated to 77% with an unused new cell.

How can i prevent this behaviour to reach initial SOH=100% with new cells? Do i have to reduce the design-capacity to the FCC-value or is there any other possibility to reach this?

I tryed to play around with "Reverse Capacity"=700 and IMAXRESRVEN=1 (in Pack Configuration D) but this seems not to take any influence to SOH-calculation.

Regards Joachim

  • 0
    TI__Guru 52115 points

    Hi Joachim,

    I woudl suggest you adjust the design capacity since you use a higher terminate-voltage.  Bascially, the Design Capacity should be adjusted to a value determined through testing using the application charge and discharge conditions.

    Andy