Wi-Fi consumes power whenever the radio is on. With older Wi-Fi network adapters, the amount of power used is generally independent of the volume of network traffic sent or received, as these systems keep the Wi-Fi radio powered at all times even during times of network activity.
Newer Wi-Fi systems that implement the WMM Power Save power saving intelligence may according to the Wi-Fi Alliance save between 15% and 40% over other Wi-Fi systems.
On Linux, the LessWatts.org initiative has also created its own Wi-Fi Power Save Poll protocol that intelligently powers off the network adapter for short periods of time to save energy.
A relatively new technology, using solar energy to power Wi-Fi routers is also an area of active research and product development.
Overall, the battery life (the length of uninterrupted operating time possible with one full battery charge) of Wi-Fi devices varies depending on several factors including:
- the type of battery installed
- the dBm rating of the Wi-Fi radio (network adapter)
- how often the Wi-Fi radio is turned off versus on
- Wi-Fi power savings modes available on the device
- the power needs of the display (screen), processor and other elements of the hardware separate from Wi-Fi