Hands on with Apple's Lightning to 30-pin Adapters
The adapters also support syncing, so if your speaker dock or dock cradle—old or new—has a pass-through 30-pin or USB port for connecting to your computer for syncing, that feature will work with the latest iPhone and iPods.
Chargers and batteries: I also tested the adapters with a dozen or so 30-pin-dock-connector chargers and batteries. As expected, most worked properly, successfully providing power to and charging the battery of the newest iPhone and iPod models. The only exceptions, as explained above, were older accessories that provide power only via the 30-pin connector’s FireWire-power pins (in other words, they don’t also supply power over the USB-power pins). These power accessories won’t work with the latest iPhones and iPods through Apple’s adapters—just as they didn’t work with recent 30-pin iPhones and iPods.
There is a workaround here, though it epitomizes the term “kludge.” A number of vendors sell 30-pin adapters that send FireWire-pin power over the USB-power pins, letting older, FireWire-only docks charge recent iPhones and iPods. A couple of examples are Scosche’s $25