Charging an Apple iPhone using a MacBook Pro

I bought my iPhone on the first day it was released. That was June 29, 2007 — well over a year ago. The battery still works well — usually lasting a full day under normal use. But if it’s taken to areas with weak cell coverage, and used extensively for maps, traffic, email, news, and so forth, it can run out pretty quickly. So it’s very nice that the MacBook Pro (and, I believe, any Mac) supports charging via USB when the computer is in sleep mode. On most PCs I’ve used, the USB ports get no power when the computer is asleep.

It isn’t always the case that Macs have power on their USB ports when asleep. When we plugged my iPhone in today (while in the car), it didn’t begin charging until the laptop was woken up and then put back to sleep. That seems to make it detect the iPhone — and once that happens, charging stays on even if the computer goes back to sleep. In fact, it seems to do this automatically sometimes.

Effectively, the MacBook Pro’s battery serves both as a battery for the laptop and also for the iPhone; as long as you’re okay with the extra heft of bringing a laptop along. I used the MacBook for a while, maybe to 80% I’d guess. The iPhone was down to less than 10% remaining, and we plugged it into the laptop until it was fully charged. When I got back to my apartment, I opened up the MacBook and found the charge level to be 57%. It appears to have taken roughly 23% of the MacBook’s battery to fully charge the iPhone.