So i broke out my trusty USB amp meter. BESTOPE Dual-USB Output Charging Detector Digital LED Ammter Voltmeter Guage DC Display 3.2-10V 0-3A Red/Blue - - Amazon.com
I know from previous bad experiences that USB power is not USB power is not USB power. First up there's all sorts of different amp chargers. Old flip phone chargers were like 350-500 mA. Whereas a new smartphone/iphone charger might be 2 or 3 amps.
Turns out the radio's usb port puts out somewhere around 1.5 amps (sorry i forget exact numbers at the moment). That might be a 'decent' charge rate to charge via usb directly but these qi chargers are more like 50-80% efficient so if you want the needle to move on your phone while charging with wireless you need to feed the qi 2amps so it can max out the wattage to the phone.
So back to the read ports- i figured they're just 'dumb ports' so hopefully chysler specs something that spits out 2+ amps so you can charge an ipod of the like. ICK- those ports are more anemic then the front port. They do just about 1 amp. From yanking the connector i surmised 2 different circuits (which is a good thing so you aren't splitting the power if you connect 2 devices)- and the amp meter indicates that is the case since they both have different readings. One of mine is actually 0.1 amp less than the other.
So none of the 3 usb ports are going to charge a modern smartphone as fast as possible.
While I happened to have the meter out i also checked how the USB negotiates power. I'm not an expert but my basic understanding is if you connect your phone into a computer/laptop then the phone initially only sucks 0.5 amps. It then requests from the computer/laptop 'hey can i get more power?' and they negotiate an acceptable level- depends on the version of USB and the like but a computer/laptop will never punch out 2+amps and that's why a tablet wont charge for spit off your laptop. If the usb port is a non-computer device then they can short some pins- or toss in a resistor or something accross the data wires and the phone will suck every last bit of power that it can and that the charger can provide.
I need to double check but seems NONE of the 3 ports negotiate or will allow your phone to suck anything more than 0.5amps if your phone is using a data cable. You can buy a cable like this (or your wallwort charger might have come with one) - http://amzn.com/B00HAAPREM
where the manufacturer futzes with the data pins to tell the phone to suck away. I confirmed with a cable like that, that the phones will max out the port. I need to dig for a known good data cable to try again but the one i had nailed all 3 ports at exactly 500 mA so the proper negotiation was not occurring. It was pretty start since the the back ports in particular bounce around all over with the amps measures but with the data cable and a phone it was nailed at 500.
So best bet if you want to charge your smartphone fast is to use a cigarette lighter adapter. Or plug a wallwort into the 110 outlet at the back of the console. It will deliver at least 2 amps that way.