Ken Shirriff:
Apple sells their iPad charger for $19, while you can buy an iPad charger on eBay for about $3. From the outside, the chargers look the same. Is there a difference besides the price? In this article, I look inside real and counterfeit chargers and find that the genuine charger has much better construction, power quality, and most importantly safety. The counterfeit turns out to be a 5 watt charger in disguise, half the power of a genuine charger.
You may have read Ken’s teardown and analysis of iPhone chargers a few years ago – now he’s looking at an iPad charger. Fascinating if you like to get into detail about this stuff.