Old topic… and that was only for (attempted) simple monitoring of the Wemos power as it was running on battery. But even then was limited as the step up converter (not to mention the internal 5v-3.3v regulator circuit) would keep the voltage indication artificially high until just before shutdown, floating ADC or not.
End result, I never really used it anyhow… 
… and I have long since switched to a voltage divider (basically added a 1.1M resistor in-line between the ADC and the battery+ to account for up to 14.8vdc) and direct 12v battery monitoring.
// Simple monitoring of internal voltage levels:
void VCCInput() {
//Blynk.virtualWrite(V0, ESP.getVcc() * 0.001);
Blynk.virtualWrite(V0, analogRead(A0)*0.0145); // ADC range up to 14.8v
}
And I already knew about all the rest… was recently explaining it to another user 