Summary. Apple recently announced that they are now selling rechargeable AA batteries with a special charger that senses when the batteries are changed to significantly reduce its standby power usage.
“The Apple Battery Charger has one of the lowest standby power usage values of similar chargers on the market. That’s the energy most chargers continue to draw after their batteries are fully charged. But the Apple Battery Charger senses when its batteries are done charging and automatically reduces the amount of power it needs. In addition, the reusable batteries that come with each Apple Battery Charger are designed to maintain a high charge capacity for hundreds of charges, so you no longer have to buy new batteries or toss them every few months.”