Just as an update to this (since I think I'll use it as a pseudo build log), I've been looking into hacking a MagSafe 1 connector onto the computer. Not sure how I want to mount it, but it might make some things a little better. For one there are some features on the MagSafe charger which are attractive. The first one being a soft-start/low current check before providing full power. The second one would be the status LED, always nice to see when things are working. I'm still thinking that I'll use the 3x1.1mm jacks and just attach either end of the MagSafe to the DC jacks.
There is a nice blog about the MagSafe connector and how it works here.
I found the internal connector on ebay, but here it is (for better pictures) on Aliexpress.
Few things that I'm not sure about though.
- Does the MagSafe version matter for the output voltage? This has to do with the fact that the micro on the connector looks for a voltage drop before applying power.
- The Switch Alpha 12 takes 19V @ 2.37A as an input (45W) and the MagSafes have a couple close contenders for the correct voltage range.
- First one is the 18.5V (85W) and second is 20V (85W).
- Does the Macbook do any communication with a microcontroller on the motherboard / or via the OS that isn't on the small, little MagSafe board?
- The connector uses a 1-wire protocol for the LED status, I might have to add in the smallest micro I can find to control the status if I want smart LED controls (as seen in the blog post).
- I don't see any chips on the internal connector, just that big black square on the top of the board. Have to say, I have no idea what it is. Looks like there is about 5 connections to it? Here is a great high quality image of the top. I think the identifier might be "L1".
- As I was writing this, I thought it might be a relay... But maybe not..
- Last thing would be how to attach the board to the computer/DC jack with good strain relief. A 3D printed case would be nice, but still lacks a good semi-permanent mounting.