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Comment by cstross | Hacker News Reader

If you miss the safety aspect of MagSafe, Griffin Technology sell a USB-C charge cable for the 12" Macbook with a magsafe-like magnetic breakaway connector:

https://griffintechnology.com/us/breaksafe-magnetic-usb-c-po...

It's not Thunderbolt 3 compatible yet but making a version that is would appear to be a no-brainer.

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Wattage issue aside, it's half an inch of protruding metal.

What I really want (and I'm prepared to pay up to $100 for) is a low-profile (near-flush-mount, maybe 3mm max) Magsafe 2 female to USB Type-C male adapter that I can leave permanently in one of the ports.

I've read that Apple have consistently declined to license the Magsafe patent, so I'd settle for a magsafe-like solution.

As I noted in another comment, it's 60W rated while the new charger is 87W http://www.apple.com/shop/product/MNF82LL/A/87w-usb-c-power-.... Confusion indeed.

Phil Schiller stated in the presentation that the new LG USB-C monitors provide enough power with 60W to charge the new 15" Macbook Pro models.

The charger offers 87W because it is meant to be able to provide enough power to charge the battery while the CPU/GPU/external devices run at 100%.

The worst you are going to experience with 60W while everything is running at 100% is that the battery isn't charging or charging very slow.

I have my MBPr (2013) running fine with a MB 60W Magsafe charger for overnight charging (think it's from my 2008 unibody MB). Been this way for 2 years, no problems.

If you're charging it overnight, you probably won't notice, but it does charge more slowly.

If you're running on the dedicated GPU with high load, a smaller adapter might not have enough power to charge the battery at all.

Yeah. You will notice that if the battery is dead flat it won't let you turn the laptop on for a bit with a 60W charger but with the 85W or whatever it is it will power up immediately.

I don't think it matters. I charge my MBP using a smaller MBA charger and vice versa with no ill effects.

It does matter that you're putting more current over the cable than it's designed for. Overloading conductors can be a melty, flamey time.

I think it just charges slower, it doesn't magically pump 87 watts over the cable, just 60.

The default condition of cables is that they can conduct much more current than is safe, and it takes extra effort to limit this. (Yes, there's a limit to what you can put through a wire, but it's enough to melt the metal, and you wasn't too avoid softening the plastic around it.) If you put twice the rated current through a cable, the conductors will handle it just fine. However, the resistance of the wires will dissipate 4× the power the insulation is designed for (twice the current times twice the voltage drop), and the inside of the isolation will get somewhat warmer. How much of a problem this is in real life depends on the ambient temperature, the thermal conductivity of the insulation, jacket, and wire, the temp the plastics can withstand, etc.

The safe thing is to use wire from a vendor that rates it honestly to conservatively, and start within the ratings.

Only if it detects it uses a 60W cable. Which I really doubt.

You can pump 100 watts through a 60W rated cable - it will probably work because the rule is "users are dumbasses, rate it for 60 on paper and 120 in reality".

Or it could heat up, maybe to the point of damage.

You guys really should spend a few moments doing a quick google search before responding. USB doesn't just magically deliver power, its negotiated between the device and the power source. In the case of USB-C, the cable is involved in the negotiation.

See slides 7&9 here specifically: http://www.usb.org/developers/powerdelivery/PD_1.0_Introduct...

More details here: http://www.usb.org/developers/powerdelivery/

Until that negotiation doesn't quite work right.

https://plus.google.com/+BensonLeung/posts/TkAnhK84TT7

It's a whole 60W A/C adapter package, not just the cable. The adapter isn't pumping out more wattage than it's rated for.

It doesn't look like it. All of the pictures show just a cable, and the description has

> In the box: BreakSafe USB-C cable with quick disconnect magnetic connector

Yes, just because you charge up a computer with a 60W A/C adapter but it can take 87W, doesn't mean the A/C adapter is all of a sudden putting out 87W. The cable itself doesn't create more or less flow.

i live offgrid and observe my 13" MBP with an 85w power supply actually pulling around 10-19 watts during typical usage...(my inverter has an output readout) FWIW... doubtless heavy gaming would be different... compiling gets it up to the upper 30s...

How do you know?

There is nothing in the cable that would prevent the current from flowing.

USB cables use resistors to indicate how much current they are rated for, so the charger would limit the current to avoid melting your cable.

(That's why out-of-spec cables are dangerous)

Well... Anything that requires more than 3 pins (which is apparently all that power requires) is going to much harder to build. A 24 pin, magnetically aligned connector seems pretty difficult to me.

As I've mentioned before, they really should have recessed this port so a solution like BreakSafe could be done and not stick out like an exposed wart. Ideally such a device would also be first-party (with 3rd party version available to reduce price).

That's a really big wart on the outside of the computer. Hopefully it won't need to be that big on the Mac.

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