My laptop charges with USB C, so when the standard charger broke, I just used the USB out port from an EcoFlow battery. The display on the battery said the laptop pulled 25-30 watts while charging. So, why can’t I use just any USB brick that can output more than 30 watts?
Is there something that is bound to go wrong that I don’t know about?
Are laptop chargers really that special?
(Edited for clarity)
The volts and amps needs to fit the laptop. Not just the max wattage.
Volts and amps are negotiated by the USB protocol. All they have to worry about is whether the source can output at least the wattage the laptop requires.
Hmm, the general use charging bricks only talk about max wattage in their listings. This might be the problem
as another commenter said, for USB-C this isn’t the case: if the wattage is correct, the charging brick and your laptop will “talk to each other” and agree on the voltage to provide
(technically there are some edge cases to this but for a high wattage supply you’re almost certain not going to have to worry about them)
DC adapters (like barrel jacks etc) you do need to match the voltage correctly
however your question is about USB-C cable, and there are different cables rated for different power delivery requirements < 60W any cable is fine, but 60-100W you need a rated cable, and then above 100W you need a higher rated cable again
… i say need here, i’m not sure if you NEED it (as it it won’t work), but the spec says that cables have to have appropriate markings so it’s probably a good rule: https://en.m.wikipedia.org/wiki/USB_Power_Delivery#USB_Power_Delivery