I always see laptops come with larger bricks that have separate mains cable which plugs into the brick. Even if the adapter has some low power rating.
Example for comparison:
On the right is a standard laptop adapter.
Same price, same connector, same protocol, same power rating, far different size.
Why is that so?
Actually, the GaN adapter on the left also advertises itself as being meant for laptops, but by default, almost all laptops will come with something like the one on the right.
Or is it simply cheaper to manufacture while being sold for the same price?
My guess is it’s similar to the electric motors they put in cars vs industrial motors… they can both put out X amount of power but the industrial ones (or in this case the laptop power) can do it continuously without overheating while the other can only output “up to” that power rating for a short time without burning up.
In this case though, the laptop power probably also outputs a higher voltage as well.
Pretty much this.
If you’ve ever tried using a phone charger to continuously power something at or near its rated maximum output, you’ll find that after a while the power becomes unstable and the charger often quite warm.
e.g. Continuously powering a Raspberry Pi or USB powered computer monitors.
People hate on bricks, but they’re still around because of heat dissipation.
Charging a phone in an hour is a lot different than keeping a laptop going for 8 hrs.
Basically ‘duty cycle’…same reason electric heaters all put out 1500W but ones for larger rooms are ‘larger’. Big or small, they both put out 1500W, but the small ones can only do it for a few minutes at a time before having to cool off, while the larger ones can run for longer and heat up a big room more quickly.
higher voltage at the same power would actually make it more compact