My work has a little power strip with a usb-c and usb-a jack on it at every desk. I can charge my phone and iPad just fine with a USB-C cable into the USB-C port, but when I plugged my MacBook Air into it, it says “not charging.” Going into the system information tool I can see it’s only running at 10W. So apparently 10W is not enough to charge, but it’s still at least keeping the battery from draining.

A 20w charger will definitely charge the MacBook, just slowly.

This was a decent USB plug from Anker. I regularly use it to charge things like iPhones and tablets. I knew it wouldn’t supply enough power to run the MBP but thought it should trickle charge the device over night. But it didn’t.

I can’t recall which cable I used though. The cable might have been garbage but I’m pretty sure I threw out all the older USB cables so they wouldn’t get mixed with more modern supporting cables.