I assume it's commonly known around here that USB cables have both wires for communicating data, as well as for sending 5V of power to the device. I commonly tether my computer to my smartphone to get internet through USB, but if I've got heavy usage, the battery in my smartphone slowly dies faster than the low power from my computer can charge it.
I'd like a special USB wire that has a micro plug on one end, but splits to two A plugs on the other. This way I can plug the data portion into my computer, but plug the power portion into the phone's normal AC adapter. I'm assuming the much higher current from the regular charger will keep the phone powered regardless of heavy usage or not.
I was thinking of making this myself, but I thought I couldn't be the first person who wanted something like this. Is there an existing wire that does what I want? Or perhaps an adapter?