Under normal operating conditions with proper wiring, a Google Nest Thermostat E charges itself automatically using power drawn from the HVAC furnace wires (utilizing either active 24V power or trickle-charging through the heating and cooling relays). However, if the system lacks a dedicated C-wire and experiences power-stealing limitations, the internal battery can drain completely, requiring temporary manual USB recharging. Verification: Monitor power voltage metrics in the thermostat settings menu to ensure the internal battery maintains a stable charge above 3.7 volts.
1 votes
Marked as accepted