Can the Apple 10W USB charger be used with a 7-port USB hub to charge iPad 2, iPhone 4S, and other devices at the same time when traveling?

When traveling, I probably will have the iPad 2, iPhone 4S, a USB backup charger, and some misc devices such as a Kindle Fire and a Sony digital camera that uses USB to charge its battery.

So instead of hooking them all up to the computer to charge them overnight, in the event that I actually need to charge every one of them that night, is it possible to use Apple's 10W USB charger that Apple makes (it is 100V to 240V compatible):

and then hook it up to any USB hub, such as this Belkin 7-port one:

and be able to charge all the devices listed above at the same time? (by the way, it seems that the smaller Apple USB charger with the green dot is 5W, so probably that one is not very powerful to charge all devices at the same time).

Solution 1:

You typically will need one high-powered (5W) USB port for each of such devices to charge efficiently. The iPad alone requires more to charge, hence the non-standard 10W adapter. In addition, the USB hub itself is not likely to provide the necessary wattage to any of the ports (these usually are low-powered ports), so chances are not even one device will efficiently charge when connected alone to such a hub.

Solution 2:

Apple use some tricky schemes to identify battery chargers and compatible devices. The sense resistor is common and it is what is responsible for the message

with some combinations of devices.

See the fun they had working out the right sense resistors when designing the MintyBoost. (and do check out ladyada.net if you like this sort of thing, there are some very clever hacks)

I don't think your iPad will charge at all with the hub. I have a Belkin Dual USB Charger and when connected the iPad just says

because it detects that it is not plugged into a high power USB port. Apple provide some explanation about high power in this technical note - basically the port starts out supplying the usual 500mA maximum and will supply extra power if capable.

The USB hub is almost certainly not a high power port, even if it is a powered hub. And it won't have the correct sense resistors to tell the iPhone/iPad that it is a device capable of charging it. So even if it could distribute power from the 10W adapter the devices could not recognise that they were connected to a 10W adapter.

If you only carry one charger then it should be the 10W adapter but you really need to connect the iPad directly to it. While the iPad can charge from the 5W adapter it will take much longer and you would probably not get a full charge on your device.

I think your ideal combination of charging devices is one Apple 10W adapter and one Apple 5W adapter, or two 10W adapters (I don't see the point of buying the 5W adapters since they are the same price and the 10W can do everything the 5W can do, it's just a tiny bit larger.)

Then you should be able to charge 5 or 6 devices a night with no problems.