Ken Shirrif did an excellent tear-down on the Mac laptop chargers.  Impressive.

The chargers are generally speaking, terrific.  In particular, it has a small microcontroller that serves as a watchdog, and turns the rest of the charger on and off when connected (or not).  This is laudable from an energy conservation perspective!

I have one pet peeve that has two root causes:

1) The outer coaxial conductor is aluminum, which work hardens and gets brittle over time, especially when the outer insulation layer gets stiffer. I think this is why the newer cables are even more problematic than the older ones.  Coaxial conductors are terrific for reducing radio noise, especially with a switching power supply, but don’t go well around tight radius curves.

2) People aren’t very good about not pulling on their cables and wrapping them tightly around corners. This is a particular problem right at the connection points on both ends. It’s fundamental to human behavior: people do what the object ‘affords,’ and cables look like they are meant to be wrapped up and pulled on. (Read Donald Normal’s “The Design of Everyday Things” for a good explanation of James J. Gibson’s “Theory of Affordances.”)

Bottom line: Apple would be well served to move away from the ‘pretty’ round coax able design and move to a flat design with more and thinner conductors, so that the strain between the outer side and inner side was reduced when going around sharper corners. Adding cable connectors so that the cable is replaceable, not just the whole charger, would also help.

(I posted a shorter version of this in a comment on Ken Shirrif’s blog.)