MBP Retina with MagSafe Auto Adapter


macrumors newbie
Original poster
Oct 1, 2014
Hello to everyone, I'm new in this community and I begin posting a newbie question even if I'm not a Mac newbie ;)

I have a car power supply from 12V of the cigarette plug to the 18.5V and 4.6A of the old MagSafe power supply. It is 85W for my old 15" MBP mid-2009.
Now I've also bought the MagSafe to MagSafe2 adapter, but I'm still wondering if I can use this power supply with my new MBP Retina 15".
Obviously the MagSafe to MagSafe2 adapter works great but I read on the new MagSafe2 85W power supply that it provides 20V and 4.25A.
Do I have problem in powering the new MBP with the power supply of the old MBP?

Someone that is using this "power configuration"?

The product is this, with exception that mine has T connector and not L connector, but this should not influence your answers.



macrumors 6502a
Apr 22, 2003
Not directly an answer, but I do use my old 85W charge with new Macbook Pro with MagSafe adapter without issue. Most likely, the higher voltage of the new charger simply charges faster.

As for a car adapter, yeah, Apple doesn't make one, and I too have purchased one of those Asian knockoffs. It works. Just be sure to check quality of the output voltage and the cables.


macrumors 68020
Aug 22, 2014
As far as I know, Magsafe 1 and 2 are exactly the same besides the power plug. The old plug was too fat to fit on their ultra thin macbook pros :p

And soon even that would go obsolete because of this microscopic 12.1 inch macbook pro coming up :p


macrumors newbie
Original poster
Oct 1, 2014
Thanks again. So, i can use my power supply with no problems :D
Any other experience with similar accessories?


macrumors regular
Feb 21, 2011
g4cube is right; assuming quality parts and construction, as long as the input power meets what the MacBook needs, the circuitry in the laptop does the regulation. The stated power specs aren’t exact, and they don’t really need to be.

I haven’t seen this adapter before, and I’d like to ask you some questions about it, if you don’t mind:
1. Is the power adapter limited to powering the laptop only—like Apple’s discontinued Airline adapter was—or will it charge the laptop battery also?
2. With the power adapter plugged in to a lighter socket, do you know what the output voltage is before it is connected to the MacBook’s MagSafe port? Do you know how the output voltage is regulated, i.e., whether its linear or switching?
3. Does the LED indicator on the MagSafe connector work the same as the one on an Apple power adapter? Does it simply show an unchanging “power on” status, or is it orange when charging and turn to green when charging is complete?
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