Using iPhone 5 in '13 Prius usb port, cables start smoking

I think this is an issue with your Prius. I have two 2013 Prius vehicles and I have used the lightening cables in both cars with my iPhone 5S without issue. My wife has also had no issue with her iPhone 5S. Taking it in to the dealer as you have said is the best course of action.

 

Get a compressed can of air and blow the USB socket on your car. Maybe something got lodged inside and it's causing a short circuit. Looking at the pic, it looks like the terminal got shorted. Have you tried plugging a different iphone/ipad on this car? I have been using mine with no issues.

 

I would've agreed with your first instinct that the cable was the problem, but it seems your troubleshooting has made that an unlikely case. I believe there is a chip inside the cable at the lightning plug end, and it's possible that poor power output from the car's USB port is causing that chip to "let out the magic smoke" as those of us in the computer industry would say. (Magic smoke is the stuff contained in every computer chip, and is the basis for how computer chips work. If you let the magic smoke out of the chip, it ceases to work.)

I'm not sure if the dealer would have the appropriate equipment or knowledge to diagnose a USB port, or if they might just be willing to replace it no questions asked... But if they hesitate, I personally would ask them to hook up an oscilloscope to the power pins and prove that it is indeed 5V (±0.25). My guess is that the car's 12V power might be leaking through instead of the intended 5V power - in which case even a multimeter should show this. A scope would be useful in case there are brief transient spikes on the power.

This type of failure is what has caused a few deaths in a couple Asian countries from third-party iPhone chargers; somebody plugs their 10¢ off-brand iPhone charger into the wall, and it sends 120V (or 240V) AC to the iPhone (and the person holding it) instead of the intended 5V DC. The 12V found in the car is significantly less dangerous to you, but not to your phone (or even the cable itself).

 

Try cleaning out the lighting port on your iPhone. While my cable never got hot, I saw that message about exceeding the power requirement while I was experiencing an intermittent connection issue with Entune. I cleaned out my phone's port and it hasn't happened since. Dust gets in the port, and the cable can't get all the way in I think. Worth a try. I also had some cables work fine and others not. Now they all work fine.

 

I'm chiming in late, but I am searching the forums for a lesser heat related issue. My iPhone (lightning) gets very much hotter when I charge it in either the console usb or using a charging adapter in the port under the dash. I use official apple cable, so that is not the issue?