OR… my “MagSafeOtomy”
The goal of this project was to get rid of my MagSafe adapter. I have successfully destroyed 3 MagSafe adapters, and don’t like the idea of paying $70 for a proprietary power adapter, and the cheap Chinese knockoffs are, well… cheap.
This was not my brightest idea… not by a long shot. I don’t recommend that anyone attempt to do this, because it was stupid. Thankfully, I don’t let stupidity or lack of forethought get in my way when I tackle a new project. By the grace of God it powers up the laptop. If not, I’m sure my wife would have killed me already for destroying an (originally) $1500 laptop.
The Magsafe receptacle at the computer-end is simply a conduit that goes straight through from the MagSafe power adapter to the computer’s power supply rails (as I discovered by forcefully tearing it from my computer and using a continuity tester). Also, the circuitry inside of the MagSafe adapter is apparently for controlling whether the battery charges, because I left center connection (charge control pin) floating when I did this, and now the laptop won’t charge. I don’t know exactly how it works, but I didn’t want to toy with it because there is a real risk of fire from overcharging with LiPo batteries. If anyone knows how it works, please feel free to edit this page.
The wire in the part of the Apple charger that connects to the MagSafe adapter contains two conductors. There is an outer conductor, which is the ground wire. Wrapped inside of that there is another insulated wire which contains the positive conductor. This measures +6.86V with no load, and +16.5V when properly loaded by the computer.
To make the barrel connection, I snipped the Apple cable, and connected a male barrel connector; making the center cable go to the center of the barrel, and the ground (outside of the Apple cable) to the inside of the cylinder.
I didn’t consider the mechanical aspects of doing this. Pulling the barrel connector out and pushing it in has already messed up my connection twice. I need to figure out something to alleviate this force; I have some car body filler so I was thinking about that. For now, I’m being careful with it.
If I had to do this again, I would have used a Dremel to maybe cut the internal MagSafe conduit out of the laptop, or at least have desoldered it using hot air. This would have been smarter than ripping if out of the laptop with pliers. I would have probably cut the conduit in half, so that the metal binding posts were still soldered to the board. Then I might have run a cable out of the hole, soldered to the binding posts. This would have been a lot neater, and I wouldn’t have had to worry as much about the strain on the connections. Also, I would not have soldered directly to the circuit board; which has caused me to rip off 3 pads because of the force of plugging and unplugging it. Oh well.
Apple MacBook power connector (MagSafe) pinout on Pinouts.ru – This is where I got the pinout diagram from. I can confirm it’s accurate. The only thing that is left out on this diagram is from the Wikipedia article linked below:
Measuring with no load will give 6.86 VDC; the full 16.5 V is provided to the proper load.