The good news is that you can buy little adapters that show charging stats to help identify the problem. They’re called power meters, and they’re fairly inexpensive. USB power meters are pretty simple ...

A meter to measure the electrical parameters ... along with the calculated power, on the small 0.5″ OLED display. The circuit is built around an ATmega328. To keep the board size small, and ...

This allows [Giovanni] to see plots of live and historical data from the power meter via his smartphone. A project like this one is a great way to explore saving energy, particularly if you live ...