My all-time favorite computer is the 11" MacBook Air, and I have a mid-2011 with a dual-core i7 and 4 GB of RAM that I like to use around the house for light-weight computing tasks. I'm currently running macOS Sonoma on mine via OpenCore Legacy Patcher, so I can run a modern browser and some light-weight macOS applications.



Years ago, the original power supply died or something, and I replaced it with a very cheap clone from Amazon. That's been fine for years, but I do find it to be very inconvenient compared to the USB-C Power Delivery supplies that I have everywhere.

I recently learned about the existence of USB-C Power Delivery to MagSafe 1 adapters and cables, and decided to give one a shot. At only about 5EUR delivered to me, I didn't have much to lose. I liked that it's just a small adapter that I can just leave connected to the Mac, and not an entire cable.



At first, it didn't seem to fit at all. I thought it was an inner diameter tolerance issue, but it turned out to be a stuck pogo pin that was causing it to not sit in place properly. I used a bit in my iFixIt driver kit to force the pin down (with a pop), and it now springs in and out almost properly. It does extend slightly less than the other pins.



On plugging the adapter into a USB-C Power Delivery power supply that supplies up to 20 volts, the USB-C to MagSafe 1 adapter seems to immediately request 20v, and uses about 0.1 amps. My concern is that instead of sensing a load before providing the full 20 volts, the adapter seems to always supply 20v out of the pins, which can cause arcing and shorting. That's not great. I can't measure it with a multimeter to be sure, as I'd surely arc and ground things. No thanks!

When connected to the MacBook Air, we see about a 1.8 amp draw, but it fluctuates depending on what the Mac is doing.



My next concern with this adapter was the voltage. According to Wikipedia, MagSafe adapters supply these voltages:

The maximum voltage supplied is as follows: 14.5 V DC for the 45 W units supplied with MacBook Air 16.5 V DC for the 60 W units supplied with MacBook and 13" MacBook Pro 18.5 V DC for the 85 W units supplied with 15" and 17" MacBook Pro 20 V DC for the 85 W units supplied with 15" MacBook Pro Retina Click to expand...

We know that MagSafe 2 is designed to be backwards-compatible with with MagSafe 1, as either the Thunderbolt or Cinema displays shipped with a passive adapter. This leads me to believe that they're all protocol and voltage compatible, and that MacBooks are designed to accept a pretty wide range of voltages through their MagSafe ports.

Here's what my MacBook Air thinks is connected:



If the MacBook determines which power adapter is connected by measuring the input voltage, then it makes perfect sense that it would see 20 volts, and determine that an 85 watt power supply is connected. This leads me to believe that supplying 20 volts to a 2011 MacBook Air is fine.

information about exactly how MagSafe 1 and 2 seems a bit scarce to me, so I'm working on some assumptions here. If you have more information or thoughts in general, I'd love to hear them. What I'd really like to find is a similar style of adapter that doesn't supply voltage until a load is detected. To me, that is the real red flag and major problem with this adapter.

Oooh - very nice! I'm going to have to get myself a few of these - i've got plenty of USB-C chargers, both Apple and otherwise but magsafe stuff is few and far between.