I don't expect the animated backgrounds to "kill" the battery tbh. If you have a couple of complications on the face which are updated everytime you glance at the watch there is also some battery consumption. Also, the screen only lights up 6 seconds if you have wrist detection activated. Can't imagine a big impact on the battery life.I really enjoy the functionality of the complications. But I would also love some customized backgrounds. Those animated ones I would assume murder the battery.