USB Amp-meter & tester voltage/current display

What is a USB Ammeter?

A USB ammeter tells you how much current a USB device is drawing. You plug the USB ammeter into a USB port or charger, and then plug your device's charging cable into the USB ammeter. It will tell you the voltage the port is providing as well as the amperage the device is drawing.

This tells you if an iPhone is REALLY charging.

If a device says it is charging, but is drawing almost no power, you know there's a hardware problem. Don't trust software to tell you what is going on with a phone. 

iPhones have very common issues that prevent charging from occuring when they say they are charging.

This is a troubleshooting godsend. 

Specific device problems end up with them drawing specific amounts of power. Once you find out what the problem with a device is, record how much power it was drawing. Now make a mental note that problem X draws 0.075 amps. Now next time that specific device is drawing 0.075 amps, you know where to look first!