A lot also depends how close you are to the hub or the nearest relay. If you're on the edge of the ZigBee range then effectively the device will have to 'shout' to be heard so will wear down the battery quicker. This also happens if yours or your neighbors WiFi channel clashes with the ZigBee channel you're using (ZigBee and WiFi number the channels differently, so google ZigBee and WiFi coexistence for a chart)