A thermostat includes a controller configured to control the thermostat, a power supply sensor connected to the controller for sensing a thermostat power source, a wireless transceiver connected to the controller for receiving control information from a remote device and for transmitting information to the remote device, and a battery level indicator for determining a remaining power capacity of the battery. The controller sets a time schedule for enabling the wireless transceiver when the power supply sensor detects that the thermostat power source is a battery. The time schedule is changed to increase a time period between when the wireless transceiver is enabled as the remaining power capacity of the battery decreases.