WARNING on USB Charging Ports!

Frozen001 wrote:
The biggest problem with the design is that it does not follow the USB Charging specifications. That specification requires different voltages present on the D+ and D- lines that allow the phone to determine how much current it can draw.

It's not clear what you're referring to. There is no "USB Charging" specification. There's a "USB Power Delivery" spec, which requires intelligence on both sides. But, that would add cost where it's not needed.

The charging ports would follow the "USB Battery Charging Specification 1.2", found here.

Note that the spec defines a "USB Charger" as "a device with a DCP, such as a wall adapter or car power adapter."

1.4.7 Dedicated Charging Port
A Dedicated Charging Port (DCP) is a downstream port on a device that outputs power through a USB connector, but is not capable of enumerating a downstream device. A DCP shall source IDCP at an average voltage of VCHG.
A DCP shall short the D+ line to the D- line.

Also see section 4.4. A DCP is by far the easiest and cheapest USB compliant port to make - 5V (1.5 A min for maximum charging, 5 A protection limit) on the power lines, short the data lines (with up to 200 ohms).

There's nothing in the spec about a USB charger pulling the data lines to different voltages for charging. That's all non-standard proprietary stuff. There are chips out there which can recognize and support devices which use such non-standard methods.