Using 85W Magsafe Adapter on Macbook Air 11,6" ?

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Using 85W Magsafe Adapter on Macbook Air 11,6" ?

Hi,

is it possible to charge the MacAir 11,6" with the powersupply of an actual MacbookPro Magsafe with 85W ?

I compared the output voltages of both supplies and it seems, that the 85W Magsafe has a higher voltage.

MacAir 11,6" / MacPro 15", Mac OS X (10.6.5)

Posted on Jan 2, 2011 12:49 PM

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Answer 1

Feb 15, 2017 12:20 AM in response to clio2k

Hi,

I am digging out this thread as I encountered the same question after my original 45W MSA was ripped apart between my desk chair's wheels....

I decided to take the risk and buy one I found on a forum, and for the last month or so everything is working fine. I have no overheating issues, over or undercharges, and no strange behaviour or readings when checking the battery cycles.

So I can say that yes, you can use it. The only issue is that the 85W one has the corner-shaped plug while the 45W one was a straight-in. So if you intend to use the usb port, you should expect some minor issues with bulky devices...

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Answer 2

Niel

Community+ 2026

Level 10

744,359 points

Jan 2, 2011 1:21 PM in response to clio2k

Click here for information.

(55878)

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Answer 3

dbs

Level 2

206 points

Jan 2, 2011 3:09 PM in response to clio2k

Using a higher wattage Magsafe charger works fine on the MBA. The charging circuit will only draw as much power as it needs.

Note that you should never use a LOWER wattage than the stock spec. But higher is OK.

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Answer 4

drsailer

Level 4

1,537 points

Jan 2, 2011 3:12 PM in response to clio2k

It works just fine. I use the 85W from an old MBP at home, and save the 45W adaptor for my travel bag.

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Answer 5

hawleyrw

Level 3

633 points

Jan 2, 2011 3:18 PM in response to clio2k

Yep - I agree with the others as I use a 60W older adapter for mine. Only issue is it partially blocks the USB port for some flash devices while plugged in. Not an issue for me.

Enjoy!

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Answer 6

clio2k Author

Level 1

1 points

Jan 2, 2011 11:29 PM in response to clio2k

Okay, thank you so far guys. Has Apple ever released a technical note for this topic?

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Answer 7

isonoise

Level 1

0 points

Jan 10, 2011 11:40 PM in response to clio2k

From what I can tell, the consensus seems to be that you can safely use the 85w MacBook Pro power adapter with the MacBook Air. Here is an Apple article (HT2346) that seems to me to suggest that it's okay to use the 85w with the MBA:

http://support.apple.com/kb/HT2346

All that said, I have not used the 85w with the Air. Because most of my work is done at a few different desks, I ordered extra 85w adapters for my 17" MacBook Pro (one for the bag/travel, one for desk one, one for desk two). The thing that bothers me (with respect to using the 85w adapter with the Air) isn't the wattage rating (85w) being higher than the Air adapter's 45w, or the current rating being higher--but, specifically, the higher voltage rating does concern me.

I understand wattage equals voltage times current. It has been my understanding that, in general (assuming tips match), that the use of higher current adapters with devices requiring lower current is okay, as long as the voltage matches. That is, I'm of the understanding that, in general, a 2-amp, 5-volt adapter should be fine with a device (for which the tip polarity and size match) requiring a 0.5-amp, 5 volt adapter. So, then, my specific issue here is that the decal on the outside of the 85w adapter does not show it auto-matching voltages down to 14.5v, only 18.5v and 16.5v.

I also read this: http://alexking.org/blog/2008/10/03/macbook-air-battery-advice

I understand my concerns may be completely without merit--electricity and power adapters are not my areas of expertise. If my concerns are without merit, though, I'd appreciate someone explaining why.

I've already purchased three extra 45w adapters for my late-2010 MBA 13". Even then, as much as I move around, it'd be great to put one or two of the 85w adapters into service for the MBA so that I have plugs at the ready at any of the spots I work at in two different buildings.

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Answer 8

Feb 11, 2011 12:25 PM in response to isonoise

I just bought a 11" macbook air and have been using it at work using the 85W magsafe from my MBP (which is now sitting at home...I have no desire to bring it out anymore. the new air is simply powerful enough for everything I do at the lab)

Uh, sorry, got distracted.

Please note that the wattage specified by Apple is the "MAX" wattage output. This and the input voltage are specified by Apple. Now, the "ACTUAL" wattage being put out depends on how much current your device draws. So when I plug the 85W magsafe into my MBA, it'll draw AT MAX 45W and that's it, simply because the design in the charing circuit in the MBA does not draw more than that.

This is also why using the 85W magsafe on my MBA won't make it charge any faster.

If you do what I've been doing and your MBA ends up dying it's because of other reasons, such as a power surge (you are using a surge protector, right?).

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Answer 9

Mar 29, 2011 3:02 PM in response to Niel

Niel wrote:
Click here for information.

(55878)

Sorry, but the post you linked to does not discuss input voltage compatibility, as the OP was asking about.

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Answer 10

Apr 5, 2011 4:57 PM in response to Steve Hoge

This is a great question but it kind of freaks me out to try, anyone can confirm?

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Answer 11

Apr 6, 2011 2:18 PM in response to travelarian

I can confirm that using the slightly higher voltage chargers intended for other Macbooks works fine on a Macbook Air 11" (Late 2010.) The Macbook Air wants 14.5 volts but charges properly on an adapter supplying 16.5 volts.

I ordered a [3rd-party car charger by PWR+|http://www.amazon.com/gp/product/B0044TNGFO|Link to PWR+ product on Amazon] that is intended for a MacBook Pro and nominally outputs 16.5V at about 60W instead of the 14.5V 45W output. It charged my MacBook Air properly using the car's 12V supply; the LED of the magsafe connector glowed yellow while charging and green when complete, and the menu bar charge indicator showed "100%".

See [here|http://support.apple.com/kb/HT2346|link to Apple Support article] for complete morphology of Apple Magsafe adapters.

-Steve

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Answer 12

rsannie

Level 1

19 points

Apr 8, 2011 1:33 PM in response to clio2k

Just for safety reasons and protecting your device, I wouldnt risk it because of the voltage output difference between the two adapters. Although I have tried using the 60W adapter for MBP13" on my MBA.

The only people that can answer this would be the engineers who designed the macbook air. There is probbably a voltage limiter of sort in the macbook that prevents higher voltage from entering the device. Otherwise, the higher voltage will eventually damage the laptop. Unless this is answered, I wouldnt risk it... I'd rather carry the extra adapter if I need to rather than have a broken laptop.

Message was edited by: rsannie

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Answer 13

Apr 12, 2011 2:16 PM in response to rsannie

The link in the post immediately preceding yours makes it clear that there is no safety concern with regard to using other magsafe adapters with your MBA. to wit:

"Power adapters for Intel-based Apple portables are available in 45W, 60W, and 85W varieties. Although you should always use the proper wattage adapter for your Apple portable, *you can use an adapter of a higher wattage without issue.*"

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Answer 14

d_and_p

Level 1

0 points

Jun 11, 2011 9:12 AM in response to anastrophe

Actually, the question is still not answered - and I am wondering too.

"Power adapters for Intel-based Apple portables are available in 45W, 60W, and 85W varieties. Although you should always use the proper wattage adapter for your Apple portable, *you can use an adapter of a higher wattage without issue.*"

This does _not_ mention using an adapter of a higher voltage. Voltages are much more important than wattages, as you can easily blow out a piece of hardware by using an adapter with a different voltage, but even the same wattage. Slightly different voltages, as other posters have mentioned, may work fine, or they may (in the case of higher voltages) overheat the system and cause damage in the long run, or who knows what else?

The OP was right to ask this question, and it still doesn't seem to have been addressed - nor do I know why Apple decided to switch voltages in the first place!

Of particular concern is this little piece: "Adapters that shipped with the MacBook Air (Original), MacBook Air (Late 2008), and MacBook Air (Mid 2009) are not recommended for use with MacBook Air (Late 2010) models. When possible, use your computer's original adapter or a newer adapter."

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Answer 15

Nov 16, 2011 7:03 AM in response to d_and_p

Watts = Volts * Amps. So when Apple says you can use an adapter with a higher wattage, this would include voltage, right? Apple only refers to *their* chargers by wattage, so when the article says a higher wattage can be used, I believe they are of course, referring to *their* other chargers.

I've never had a problem using a higher wattage adapter. In fact, I'm thinking of ordering a few more cheap 85W spares for my MBP 13", so I have an adapter ready at my desk, couch, etc. Flash content (Youtube, .etc) is a battery drainer!

It also seems the 85W does not get near as hot charging my MBP as the 65w does. YMMV.

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