I always thought the circuit that takes care of the charging currents is inside the laptop, the power adapter is just providing the juice, I thought.
If that were the case, all they would need is straight wire, correct? Every cord I've seen has the brick attached somewhere in the middle.
I'm no sparksmith, so I lack the proper vocabulary.
There's a difference between something that provides constant juice and soemthing that charges.
Just like the power above me said, I thought the brick is a transformer. And since those devices are more or less usable for different laptops, which all come with different batteries, I thought the laptops themselves are equipped with the circuits that take care of the charging, ie, decide the mA output and the duration. Maybe I'm wrong, but from seeing opened cellphone and laptop batteries I assume most of the charging circuits actually come with the batteries themselves.
The brick just tries to provide whatever volt at whatever maximum ampere amount as reliable as possible.
At least that'd make the most sense to me.
BTW, somebody above said it's THAT hard to design proper chargers. IIRC, once you get a reliable power source, it isnt, at all. At least not, when you know what kind of battery you're charging. And with that I dont mean current and capacity but what materials the batteries are made of. Maybe it's hard to get a charger to be usable for all kinds of different batteries or make it detect what kind it is charging (if that's even possible).
But regulation of a charging cycle... IIRC thats pretty basic stuff. You can even charge batteries (isnt there an english word to discern rechargable batteries from "normal" ones? dont you say "accumulator" or something?) yourself with a proper power source, a watch, and some pretty basic maths