USB-C to MagSafe 1 and MagSafe 2 Mac Laptops

And we come ’round full circle ... My foray into USB-C battery packs (and upgrading to 2020+ Apple hardware, decent keyboards and USB-C charging without an intermediate inverter and AC adapter) all started with wanting a portable setup for a full day of (at least intermittent) computing without access to a 110V socket. Back then, a USB-C to MagSafe 1/2 adapter seemed like a not great idea (ignoring all the negative reviews), as I didn’t have a battery pack that could deliver 60+ watts continuous. But now I’ve got several (Zendure SuperTank Pro, Shargeek Storm 2, etc).

The MagSafe connector actually has a bit of intelligence built in: Teardown and exploration of Apple's Magsafe connector. Meanwhile, the power profiles appear to be pretty straightforward:

MagSafe 2 85 W: 20V⎓4.25A
MagSafe 85 W: 18.5V⎓4.6A / 16.5V⎓3.65A
MagSafe 2 60W: 16.5V⎓3.65A
MagSafe 60W: 16.5V⎓3.65A
MagSafe 2 45W: 14.85V⎓3.05A
MagSafe 45W: 14.5V⎓3.1A

The two 100W ports of the SuperTank Pro supports 5V⎓3A, 9V⎓3A, 12V⎓3A, 15V⎓3A, 20V⎓3A, and 20V⎓5A, while the Storm 2 can deliver via its 100W port 3.3-21V⎓5A, 5V/9V/12V/15V⎓3A, 20V⎓5A. So, either solution should be able to power at least a 45W MacBook Air. And I have those 11" 2015s with Core i7 processors and 8GB RAM that are pretty able performers generally (and that 2010 13" Core 2 Duo 4GB machine that, if it died, I wouldn’t be crushed; it’s enough to be usable, but just barely, and certainly doesn’t encourage screwing around idly). Wanting to reduce the cost of the kit I’m subjecting to all the impacts and injuries of a theme park trip, and reading about a guy successfully using a similar piece of kit to power an older ThinkPad ... Against my better judgment I’m going to try this:

AreMe USB C to Magnetic L-Tip Charging Cable

(They also sell a T-tip version that appears to be a MagSafe 1 adapter. I’m going to try this on my 2010 first and see where that gets me; I have a couple of the Apple MagSafe 1/2 adapters I can use to trial it on newer hardware. If it works at all, I’ll probably pick one up for the newer Airs.)

It will be here tomorrow. I’ll be running it against the Klein, with the Zendure, etc., as I do.

Part of me is leery about the cables (seems like the cable part is where these things fail, if they fail), but for an initial proof of concept phase I kinda wanted to eliminate as many variables as I can. (Is this cable a 60W? 100W?) But if this experiment works I might try again with, e.g.:

apexsun Magnetic L-Tip USB C Adapter and/or T-tip Adapter (which very specifically states it will work with a 20V⎓2.25A (45W) or 20V⎓3A source, and a 65W USB-C PD cable); or

RAINSUNG Female USB C to Gen 2 T Tip Cable Adapter (ditto; drinks 20V⎓2.25A (45W), 3.25A (60W), or 4.25A (85W)); or ...

One thing I’m anticipating, based on my experiences with cheap third party chargers, is a constant power supply to the power pins. Paraphrasing Ken Shittiff’s blog post (and, edit: this great summary in a YouTube video): Quality MagSafe 1/2 adapters start by supplying a low current (~100 µA 6V (3V for MagSafe 2)) signal on the power pins. The Mac then pulls the power input low to ~1.7V through a resistive load, and when the charger detects this, after 1 second the charger will switch to full voltage. When the Mac detects full voltage, it then reads the charger ID via the middle (sense) pin, and if everything’s kosher, switches the power input to the internal power conversion circuit and switches on the appropriate LED (again, using the sense pin). The cheap chargers appear to supply full power at all times, hence why they’ll sometimes spark as you’re connecting them. Having the MagSafe end already connected to the laptop before applying USB power should minimize those risks, however (and if the cable gets pulled out, simply disconnect it from the USB source before re-attaching).

Now, all of that said, battery packs that can supply the 60W needed for an Air are few and far between, especially below the $150 price point. The only one I’ve found from a reputable manufacturer I’m familiar with, in fact, is the Anker Portable Charger, 737 Power Bank (PowerCore III Elite 26K) Combo with 65W PD Wall Charger, which is $120 as of this writing. That bundle consists of a  PowerCore III Elite 26K 60W (model A1290) battery pack (25600 mAh stated capacity), together with a 65W Anker 515 wall wort). That battery pack should work - finally found the specs, which do in fact list 20V⎓3A (and somewhat surprisingly state the maximum output is 78W, so you can apparently use one or both of the USB-A ports to power or recharge other devices, like a cell phone, while supplying 60W to the laptop. My search didn’t find, but I found saved in an Amazon list, another – lower capacity — version, the Anker Portable Charger, PowerCore III Elite 19200 60W Power Bank Bundle with 65W PD Wall Charger bundle, that’s only $80, and purports to supply 60W from the battery pack. Also, searching for the manual / specs for the 60W PowerCore III Elite, I stumbled across an 87W version of the same thing, which should supply (20V⎓4.35A) a non-Air MacBook, though those are a penny less than the $150 threshold where the next level starts (e.g., the Storm 2 / PowerTank Pro are regularly available for $170 or so).

 I can’t find a list of its supported PDOs anywhere (but I’m not familiar with any USB-C PD spec delivering 60W at anything less than 20V). (In fact, 

(Exploring USB-C PD a bit more ...  If I’m reading this right (p. 13), 5V tops out at 15W (3A), 9V at 27W (3A), 15V at 45W (3A), and 20V starts at 45W (2.255A) and goes up to 5A for 100W...?) (And of course devices can supply lower current; e.g., the PowerCore 10000 supplies “20W” or 9V at up to 2.22A (19.98W).))

MacBook Air charging from a USB-C PD Battery Pack

Update: The adapter arrived, and works! I have it hooked up (through an Apple MagSafe to MagSafe 2 Converter) to a MacBook Air I picked up for like $200 on eBay, a little battered but not too bad and fully functional. 

It’s a 2015 11" Core i7 2.2 GHz with 8GB RAM and 128GB SSD. (Which, now that I’ve made it a viable, usable totable, I might want to swap out for something larger... Best bang for the buck seems to be the 1.0TB Aura N2 for $99. Or, an NVMe adapter and a $50 1TB drive...)

The battery on this machine, despite being ~6 years old, is in pretty good shape, 633 cycles and coconutBattery is still reporting it as having ~90% of its design capacity remaining.

It took about 40 minutes to charge from 71% to 100%, using the AreMe cable (and Apple’s adapter), with the screen on at about 75% brightness, WiFi on but minimally used, etc. The Zendure battery pack dropped from 100% to 83% (-17%) to bring the Mac up 29%. (coconutBattery reports the battery at 95.6% while macOS Monterey says it’s 100%...)

coconutBattery screenshot

Interestingly, the light on the AreMe cable is reversed from Apple’s standard; the Apple adapters glow orange when charging, green when charged. This is green when charging, orange when charged.

A full scope solution would include a charger, probably the most cost-effective is the Anker 715 (65W) ($45), which I have at my Rigg workstation. The SuperTank Pro (at least) supports pass-through charging. Plug the 715 into the wall, connect it to the SuperTank Pro with a high current cable like this Anker 100W 10 footer, and then plug the Mac in to the SuperTank via one of the AreMe cables and Bob’s your uncle.

(Twenty minutes later, it’s continuing to trickle charge; the Mac still shows 100% in the battery widget, but coconutBattery is showing it’s charging at ~3.5W and the current charge has risen to 4544 mAh of a full charge capacity of 4639 mAh (98%). The SuperTank is reporting a draw of ~10-15W and is down to an 80% reported charge. An hour and fifteen minutes in, coconutBattery was reporting 100% charge, and the SuperTank was down to 77%.)

I’m happy enough with this proof of concept, I’m going to get the T-Tip cable that’s native to the newer MagSafe 2 machines, so I won’t have that tiny adapter to inevitably lose.