Here is a simple test to test the iPad Mini Battery using a cheap & simple power meter. It shows the time needed to charge the battery and how much energy is needed to charge the iPad Mini battery to 100%.
Ipad Mini Battery Test
A simple test to test iPad Mini battery charging is through a Power Meter;
When the iPad Mini is connected to the Power Meter, it shows actual power [Watt] used at any moment in time. Simultaneously the Power Meter counts the total electricity consumption [Wh] of the Ipad Mini over time.
The power meter shows 7.1 Watt when the Ipad Mini is charging with the screen on. This is about the maximum power the iPad Mini AC power adapter takes from AC mains.
Ipad Mini Battery Charging
With 44 % battery capacity left, the Ipad Mini is charged with the power meter connected. The screen is turned off by pressing the sleep button on the side of the iPad mini.
About every 10 - 15 minutes the charge progress is logged with paper & pencil. The result is the following curve;
The blue dotted line shows the Charge State reported by the iPad Mini. It runs from 44 % to 100 %.
The pink dotted line shows the energy (Wh) measured by the Power Meter and supplied to the Ipad Mini. It runs from 0 to 15 Wh.
The Ipad Mini is charged in 150 minutes from 44% to 100% and it took 15 Wh to do that.
The Ipad Mini has a 16.3 Wh battery, which is close to the 15 Wh already supplied.
During charging the iPad Mini AC Adapter heats up to about 59 Celsius (138 Fahrenheit) in an ambient temperature of 21 Celsius (70 Fahrenheit).
Part of the energy (Wh) supplied is dissipated in heat in the AC adapter, the rest goes to the iPad mini.
It took 15 Wh to charge the 16.3Wh Ipad Mini battery, from 44% to 100 %.
The power lost during charging is 15 Wh - (56 % * 16.3 Wh) = 5.8 Wh. Part of this loss is the heat caused in the AC power adapter.
Below a few power meters;