Coming in VERRRRY late to the discussion, I would like to add that using some power adapters with excessively high current ratings
can damage equipment. Say that you pick up a really cool looking, medieval 5V, 10A power adapter and hook it up to a couple of 7400 series chips for a school project. And they blow right up and smoke and bubble. WHY?? It was the right voltage and you only needed 1 mA! It was not actually the right voltage when you ran it with such little current.
Unless a power adapter contains a regulator to overcome it, it has internal resistance that directly affects the output voltage over the entire range of current, starting at
zero. When this 5V, 10A adapter was designed, it may have initially had an open circuit output voltage of 5V, but when test technician intern ID X hooked up his awesome heatsinked potentiometer from high school to load it down, something
very bad happened.
He dropped the resistance lower and lower while watching the current climb, and while one might expect this resistance to be 0.5Ω after visiting Ohm's law (5V ÷ 10A = 0.5Ω), he actually had to turn the resistance all the way down to 0.27041Ω before he reached 10 Amps. Then he tested the output voltage under this load and it was WRONG - 2.29587V. Well he can fix that.
So, eager to get this thing working and impress the other guys in the only way he knows how - sheer SPEED, the guy cracked open the transformer and began adding extra output windings to the transformer. Current and voltage went up a little with each extra winding, so he had to turn up his pot a little each time too. Finally, after more than doubling the magnet wire that was there originally, he was satisfied when his readings were 5V, 10A. So was his boss - it does exactly what the spec says - 5V at 10A. TEST PASS --> TIMELINE OBJECTIVE COMPLETE AHEAD OF SCHEDULE --> SHIP IT --> PROMOTE INTERN X TO COFFEE MACHINE SUPERVISOR --> HAVE A REFRESHING CUP OF COFFEE. (Kidding in Dilbert fashion of course.
)
Going back and testing the power adapter for open circuit voltage after this modification, it is now 10.889V because of 0.22959Ω internal resistance! Test the open circuit voltage of handful of your power adapters to see how true this story actually is.
Seriously, though, companies are VERY likely to be aware of this as they select/design power adapters, and they choose the most cost-effective one that works fine specifically with the device they bundle it with. When we try to use a high current rated adapter with a low current device, even if it's the same rated voltage, that's where we could run into problems if we don't consider voltage under different loads. I don't know if this applies to the PowerBook vs Portable power adapters damaging the PowerBook 100 but it could be tested.