The article presents the power consumptions measurements performed for three wireless routers operating in IEEE 802.11n standard. A typical consumer-class device Asus RTAC66U was chosen, an operator-class Gateworks Laguna GW2387 and a router built based on the Raspberry Pi3 platform. The aim of experiments was to test the influence of the beacon interframe interval, a client association (joining) in the network and the transmission itself, on the lifetime of battery-powered devices. Theoretical calculations were also performed for the influence of the analyzed scenarios on the battery-powered devices.