STC3117: SOC level of Ri referred to by datasheet

[msz]

For calculating the VM_CNF value the datasheet of the STC3117 gives the follwoing equation:

VM_CNF = Ri * Cnom / 977.78,

where Ri is the impedance of the cell.

The impedance of the cell however depends on the SOC, so i wonder at which SOC the Ri is supposed to be measured for use with this equation.

Any ideas?

[Winfred LU]

It would be the initial resistance measured at 50% SOC.

[msz]

Hello Mr. Lu,

thanks for Your quick response.

>It would be the initial resistance measured at 50% SOC.

measured at 1kHz sine i assume?

kind regards,

[Winfred LU]

Yes, the resistance is measured at AC 1kHz 50% SOC.

The value is usually available in the spec of the battery.