Power::readPowerStatus is called on startup,
but AnalogBatteryLevel::getBattVoltage
skips the read because 5 seconds have not
elapsed since last_read_time_ms, which
is initialized to zero.
`batMv=3100` is reported because
AnalogBatteryLevel::last_read_value is
initialized as:
```
float last_read_value = (OCV[NUM_OCV_POINTS - 1] * NUM_CELLS);
```
