Magsafe 2 expansion card

Hi all, does anyone have any plans on working on creating a magsafe 2 expansion card? Does anyone have any idea how magsafe 2 works. The new version of magsafe seems super cool and I have access to a lot of these chargers but I cant use them. I thought that my framework can probably take it, I just don’t know where to start? any advice/help would be greatly appriciated :slight_smile:

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You want to create something like the magsafe 2 powerbank?

That would not be very helpful for laptops, as they have a much higher rate of discharge and need way more power than something as small as magsafe could deliver.

If you are looking for a cable, someone has already done this.

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I think they were referring to creating an expansion card that can use one of Apple’s MagSafe 2 charging cables, which are used for MacBooks, because they are often around people who use MacBooks.

This cable is not to be confused with:

  • MagSafe (Gen 1) for MacBooks
  • MagSafe 3 for MacBooks
  • MagSafe for iPhones

Love Apple’s clear and unambiguous product names :man_facepalming:

edit: like this cable: Apple 85W MagSafe 2 Power Adapter - Apple


Yes, sorry for the poor wording on the original post, I want to know how possible it would be to create an expansion card that takes in Magsafe 2. I have no idea if it can be converted to USB-C and if so how so I was wondering if anyone was looking at doing anything similar

It should be possible. Per the Wikipedia article on MagSafe, the outer two pins are GND, the inner two pins are VBUS (either 14.5, 16.5, 18.5, or 20V DC), and the middle pin is a data pin that allows the charger to know information about the charger (power usage and serial number) and output LED values for charging accordingly.

I’ve seen female USB-C boards that are programmed for a specific voltage, and while I know male boards exist as well, I’ve yet to find one (if anyone knows of any, please link to them). Basically, the way I would solve this is by getting a 20V version of a male USB-C board and hardwiring its V+ and GND pins to a 20V version of the MagSafe port. I may be overly simplifying here, but the existence of these MagSafe to USB-C cables that are hardwired for either 15V or 20V (I have linked to the 20V MacBook Pro version) leads me to believe that this should be possible.

Further update - This MagSafe to USB-C female adapter reminds me a bit of the card that was requested here, but it’s still not quite the same thing.

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Keep in mind that any adapter made here will have the potential to destroy whatever port it’s plugged into. Especially if the adapter has data lines connected instead of just power.


This would indeed be neat to see, I do agree. However, it may be prohibitively complex due to Apple’s proprietary negotiation method that is built into the MagSafe technology. Effectively, there is a chip inside the MacBook that communicates with a chip inside the power adapter using that center data pin that was mentioned above. The communication is non-standard from what I’ve read, and is used to determine how much power the laptop is capable of receiving safely at any given moment. If you have a MacBook, you can observe this when plugging in the MagSafe charger (v1, v2 or v3) and noticing how the amber light does not illuminate immediately when attaching the connector. The negotiation takes place to determine the available charge level, temperature of the battery, capacity of the battery, and also takes other factors into effect such as low power mode. This ultimately gives the power adapter the “green light” to pump however much power the laptop is asking for, at which point the connector will illuminate orange. Once the battery has reached a full charge, the laptop communicates with the power adapter to stop sending power, which also illuminates the light green. There is also some useful info on how MagSafe works here, where it was attempted to bring MagSafe to a Mac Mini with a DIY project but ultimately failed due to the technical complexity of this negotiation: We made the Mac mini ACTUALLY mini! - YouTube

Hope this helps!

Ever changed a worn cable on a MagSafe 1 PSU? The Cable only has 2 wires in it. There is no communication in there except to turn the led different colors.

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That’s intriguing @blkhawk, so presumably a MagSafe 1 expansion card could be possible, or at least easier than MagSafe 2.