Batteries have come a long way… you can particularly see this from mobile phones. A decade ago they were the size of bricks and last 4 hours on standby. Phones came with a second battery as standard. Today a Nokia can last a week on standby and light usage. So they have come a long way but still not far enough by any standard. You see we talk “wireless”. But really they are not wireless at all. Wires seem to be everywhere. When I can use a cord cover I do, but still there are wires everywhere!!
One day wireless will really mean wireless… hopefully in not too many years!