USB port not charging my phone

Sorry but that's a ridiculous statement to make.
It is like saying that a water faucet sucks water out of the pipe.

The simple fact is that most radio heads in cars provides only a minimum amount of power. In most cases, it will run your device with a tiny bit left over for charging. In some cases it may not be enough to change at all if the device is in use.

 

It all started when Apple decided to use the USB-A connector on its chargers for devices that violated the current requirements of the USB specification.

 

That's how it works. The AC power outlets in your home work the same way. You can plug a 15A car charger into a 10A circuit and it won't care, it will draw the 15A until the circuit breaker trips or a fire starts.

This is why the phone must discover how much current it can draw and it is why a USB port which provides higher current to an iPhone might not provide the same current to a Samsung phone.