I decided to do the following test: - First and foremost, run the device’s battery down to zero. And by that, we mean the device runs completely out of juice and powers down on its own. - Next, charge the device’s battery all the way up to the 100% mark. I tried this with the Pro 9.7 256 GB wifi+cel, used less than a week, and bought a month ago. Once the device was turned off and I connected this iPAD to the original charger, the clock started. All the time I let it closed (not using), with the Smart Cover, and in airplane mode. It took exactly 3 hours and 42-43 minutes to reach from 0 to 100%. This iPAD has only 3 full cycle charges. It's the MLQ62CL/A model. I'll conduct this test again, this time with the 4, that was used practically everyday since I bought in 2013, and post the results here, later.