BAT Voltage Calibration is shown in Figure 2-2.

Figure 2-2 BAT Voltage Calibration

1. Apply known voltages in mV to the voltage input:
   • VBAT between VC4 pin and VSS pin
2. If ManufacturerStatus()[CAL] = 0, send 0x002D to ManufacturerAccess() to enable the [CAL] flag.
3. Send 0xF081 or 0xF082 to ManufacturerAccess() to enable raw cell voltage output on ManufacturerData().
4. Poll ManufacturerData() until the 8-bit counter value increments by 2 before reading data.
5. Read ADC conversion readings of cell stack voltage from ManufacturerData():
   • ADCBAT = GGgg of ManufacturerData(),
6. Average several readings for higher accuracy. Poll ManufacturerData() until ZZ increments to indicate that updated values are available:
   • ADCBAT = [ADCBAT(reading n) + … + ADCBAT(reading 1)]/n
7. Calculate gain value:
   Equation 2. $BAT Gain = \frac{V_{BAT}}{{ADC}_{BAT }} \times 2^{16}$
8. Write the new BAT Gain value to data flash.
9. Re-check voltage readings and if these are not accurate, repeat steps 4 – 6.
10. Send 0x002D to ManufacturerAccess() to clear the [CAL] flag if all calibration is complete.