There are also supported outputs on a charger, and usually the maximum power output mode is the same as the optimal input for a laptop it came with.

I think there should be written somewhere what the computer needs. For example 20V 3A ~ 60W. I don’t know how much voltage the super fast phone chargers have, but looking only at power isn’t enough.

Just for curious readers: I noticed some annoyance with my laptop, it has 100W mode, but only with the original charger. So just plugging it into a dock with original charger attached limits the laptop to 65W only. And if I tried (mainly out of curiosity) charging with an insufficient phone charger, CPU switched to 300MHz and everything got very laggy. The same thing happened when I connected two of the USB ports together :D