So, I stumbled across an Apple Support article about which power adapters to use with which computer. The rule of thumb, since the mid-90’s, is that more demanding models come with adapters that provide more power: MacBook Air (45W), MacBook Pro 13″ (60W), MacBook Pro 15″ (85W). It’s labeled on the brick part. It’s safe to use a larger adapter than the one the computer came with, but not the other way around.
Well, the same story is true for the new models with USB-C charging ports: MacBook (29W), MacBook Pro 13″ (61W), and MacBook Pro 15″ (87W). As before, you can’t use a brick smaller than the one the computer came with. New connector, same rules. The only difference is that now the charging cord is detachable, rather than being permanently attached to the brick.
Here’s what’s crazy: according to the article, the rules also apply to the charging cord. If you have a MacBook Pro, you have to use the cord it came with. You can’t use the one that comes with a MacBook.
The best part is that the two cables look identical, so Apple suggests you identify them by searching for the serial number printed on the cable, in the teeniest, tiniest, faintest little letters. It took me about 10 minutes to find it, and I had to zoom in with the iPhone camera to read it. (Apple’s article also says that you can’t use the MacBook Pro cable to charge a MacBook, but that doesn’t make sense, and I suspect it may not be true.)
So, if you have both a MacBook Pro and a MacBook, I’d suggest you mark both the brick and cord (like with the same squiggle or something) for each so that you know they go together.
I’m hoping that since the MacBook Pro came out after the MacBook, this is a temporary situation, and that the next revision of the MacBook will utilize a cable that can be also used with a MacBook Pro. Otherwise, Apple’s gonna be asking for a lot of support calls when Macs aren’t charging correctly.