Delete comment from: Ken Shirriff's blog
Ken, thanks for the detailed teardown of the MagSafe2 connector. As an avid DIYer, I appreciate contributions of this caliber and it definitely helped me survive the panic I fell into while hacking at a way to extend my Mac Book Air 2013 usable battery supply. I travel a lot and often find it difficult to keep me laptop charged. I've replaced the internal battery several times now through the years but 55Wh still only gives me about 2hrs of usage. So I bought this power bank and figured I'd rig a MagSafe2 cable to it:
https://www.amazon.com/gp/product/B011BGPUSI/ref=oh_aui_detailpage_o05_s02?ie=UTF8&psc=1
Here's a shot of the cable I made by chopping up the one that came with the power bank and reusing an old MagSafe2 cable I had from a previous fix.
https://cloud.githubusercontent.com/assets/876837/25307523/48018dd0-2770-11e7-8694-d18a3c65111c.JPG
Without giving it much thought I just plugged the cable into the DC out of the power bank and into the Mac Book Air.... and, nothing happened. No LEDs, no indication from the Mac that power was being delivered. I then plugged in my formal Apple power adapter and nothing either!! That was the cause of my panic. I figured I somehow fried the internal power jack i/o board so immediately searched and ordered one online. While waiting for that to arrive, I continued to wonder what happened.
First thing I realized was the power bank can deliver different DC OUT voltages and defaults to 5V from the factory. It's hard to believe that would have damaged something so I reset the SMC and PRAM on the Mac to see if that would help:
https://discussions.apple.com/docs/DOC-3604
Still nothing. So then I set the power bank to 16V to match the Apple power adapter output and tried that (what the heck). It worked!! LEDs and the Mac started charging. Phew! something is working. Then I checked to see if the Apple power adapter would work and disappointingly, it didn't. That was weird. Perhaps the state of the charger was persisting the failed condition so I
unplugged it from the wall and waited some time for the caps to drain. Plugged it in again and indeed it worked! So now the Mac is charging both on the original Apple power adapter and my rigged power bank setup.
I'll return the repair stuff I ordered and hopefully be good to go from here on out.
Apr 22, 2017, 3:53:05 PM
Posted to Teardown and exploration of Apple's Magsafe connector