When my son was born, and his vibrating bouncy seat started eating through AA batteries like jelly beans, I bought rechargeable batteries. But I found them kind of a pain. They didn't always charge back up very well, and it took a long time to charge them. Therefore, the battery charger is now in a drawer, and while we still go through AAs like crazy for all those electronic toys, I just buy regular batteries. But if this concept design comes to light, I might just switch back. Continuance is a battery with a USB port right in the side.