1 2 Previous Next 15 Replies Latest reply: Dec 5, 2012 5:35 PM by Csound1
Tuffy Nicolas Level 2 Level 2 (165 points)

I have a 15" MacBook Pro.

 

I also have an 11" MacBook Air.

 

Both came with the standard white charging cords.

 

However the white square "brick" in the middle of the Pro's charging cord is slightly larger than the white square "brick" in the middle of the Air's charging cord.

 

Problem: I am going traveling with a partner, and one of us will be bringing the Pro, and the other will be bringing the Air. We need to travel as lightly as possible, and I'm looking for a way to NOT bring anything I can possibly leave at home. It dawned on me that we were not only bringing two computers, but also two charging cords. The Air's charging cord in fact practically doubles the weight and volume of the Air as a long-term traveling device, since the Air itself is so light and takes up so little volume.

 

It would be great if we could bring just ONE of these charging cords, and use it (alternating back and forth, of course) to charge up BOTH computers.

 

So my question is:

 

If I JUST brought the Air's smaller charging cord, it obviously can successfully charge the Air, but can it ALSO charge the Pro?

 

OR...

 

If I JUST brought the Pro's larger charging cord, it obviously can successfully charge the Pro, but can it ALSO charge the Air (safely)?

 

Or does each computer necessarily require its own specific charging cord, for whatever electrical-requirement reasons?


15" MacBookPro, Mac OS X (10.6.5)
  • 1. Re: Will my MacBook Pro charging cord safely work to charge my MacBook Air -- and vice versa?
    tjk Level 7 Level 7 (24,150 points)

    Hi T,

     

    The MBA uses a 45watt charger.

     

    The MBP uses an 85watt charger.

     

    I've never tried it, but I sure would never try it on my machine or any machine anyone cared about. 45 will not charge the 85 properly, and 85 could possibly (probably?) cause damage to the MBA.

  • 2. Re: Will my MacBook Pro charging cord safely work to charge my MacBook Air -- and vice versa?
    Tuffy Nicolas Level 2 Level 2 (165 points)

    Hmmmm...but I just finished talking to a "genius" at an Apple store (before I saw your answer) and he told me that the Air's plug would not charge the Pro (as you describe), BUT that the Pro's plug would indeed safely charge the Air, with no risk of damage.

     

    Are you basing your advice on general wisdom about how electronics works, or on specific knowledge concerning the way Pros and Airs interact with power cords of different types?

  • 3. Re: Will my MacBook Pro charging cord safely work to charge my MacBook Air -- and vice versa?
    Csound1 Level 8 Level 8 (35,470 points)

    You can safely charge the MBA with the charger from the MBP, the MBA charger will not supply enough power to charge the MBP.

     

    The MBP charger will not damage the MBA, the MBA will draw what it needs (45w) so the MBP charger will not have to work very hard.

  • 4. Re: Will my MacBook Pro charging cord safely work to charge my MacBook Air -- and vice versa?
    tjk Level 7 Level 7 (24,150 points)

    Tuffy Nicolas wrote:

     

    Hmmmm...but I just finished talking to a "genius" at an Apple store (before I saw your answer) and he told me that the Air's plug would not charge the Pro (as you describe), BUT that the Pro's plug would indeed safely charge the Air, with no risk of damage.

     

    Are you basing your advice on general wisdom about how electronics works, or on specific knowledge concerning the way Pros and Airs interact with power cords of different types?

     

    As you said, "general wisdom" (with more emphasis on the "general" than the "wisdom" ). I do not dispute what he said, but if I were in the Apple Store, I'd have him show me on their machines before I'd even think about trying it on mine. And I have to say, from what I know about charging and over charging lithium batts, that is probably still not something I'd try on my equipment. Of course ymmv. I hope you'll post back with results.

  • 5. Re: Will my MacBook Pro charging cord safely work to charge my MacBook Air -- and vice versa?
    Csound1 Level 8 Level 8 (35,470 points)

    Hi tjk

     

    Power drawn from a supply is governed by the load (MBA) not the charger, thus: a 45w load (MBA) will draw 45w, the MBA charger can deliver 45w so all is well, the MBP charger can supply 85w so all is also well (only 55% of it's capacity is being used)

     

    Conversely the MBP will draw 85w and will be just fine with it's own charger (which can supply 85w) but will only be able to draw 45w from an MBA charger so will not charge.

     

    I'm a certified low & high voltage tech, and I have a heap of Mac portables.

     

    To the OP

     

    Go ahead with your plan, no damage will result.

  • 6. Re: Will my MacBook Pro charging cord safely work to charge my MacBook Air -- and vice versa?
    tjk Level 7 Level 7 (24,150 points)

    Csound1 wrote:

     

    Hi tjk

     

    Power drawn from a supply is governed by the load (MBA) not the charger, thus: a 45w load (MBA) will draw 45w, the MBA charger can deliver 45w so all is well, the MBP charger can supply 85w so all is also well (only 55% of it's capacity is being used)

     

    Conversely the MBP will draw 85w and will be just fine with it's own charger (which can supply 85w) but will only be able to draw 45w from an MBA charger so will not charge.

     

    I'm a certified low & high voltage tech, and I have a heap of Mac portables.

     

    To the OP

     

    Go ahead with your plan, no damage will result.

     

    Thanks for the explanation C, I appreciate it.

  • 7. Re: Will my MacBook Pro charging cord safely work to charge my MacBook Air -- and vice versa?
    Csound1 Level 8 Level 8 (35,470 points)

    You're welcome

  • 8. Re: Will my MacBook Pro charging cord safely work to charge my MacBook Air -- and vice versa?
    Tuffy Nicolas Level 2 Level 2 (165 points)

    OK, thanks, I gave you a "correct answer" marking.

     

    One final afterthought:

     

    The "genius" said that the Air's power supply might be able to supply some power to the Pro, but that it simply would take extra-long for the Pro to get recharged using only an Air's power supply...however, he was not sure about this detail, as he had never tried it. In your experience, in a situation like this in which a power supply is just recharging a battery, rather than powering a device directly, could it be possible for an under-rated power supply to slowly slowly slowly trickle in enough electricity to a higher-rated battery to eventually recharge it -- or  will the Air's power supply do no good whatsoever on a Pro?

     

    Not a big deal, just curious about this one last aspect.

  • 9. Re: Will my MacBook Pro charging cord safely work to charge my MacBook Air -- and vice versa?
    Csound1 Level 8 Level 8 (35,470 points)

    That is also correct, the MBA supply will deliver approximately half of the energy the MBP needs to run & charge, this means that while it's in use it will discharge until either (a) flat, or (b) switched off. I would use the MBP charger for both machines (if you are intending to carry only one charger with you)

     

    And thanks for the points.

  • 10. Re: Will my MacBook Pro charging cord safely work to charge my MacBook Air -- and vice versa?
    garylapointe Level 1 Level 1 (20 points)

    I was wondering about this myself.  I have an 11" Air and a MacBook Pro.  I keep the Air charger in my backpack, but occionally I take the MB Pro with me and I have wondered if it would charge (or maintain the power for my MB Pro).

     

    It's rare I run the battery down, but I feel the need to have a spare charger with me.

     

    But Apple makes the Apple MagSafe Airline Adapter

    "With the MagSafe Airline Adapter, you'll never again worry about losing power while traveling. Just plug it into your airline seat power port and keep your MacBook, MacBook Pro, or MacBook Air computer powered up for the entire flight." and

    "Using the MagSafe Airline Adapter provides power for your computer but does not charge the battery."

    But they have no distinction between the MB.  I don't believe this is supposed to charge your MB, just maintain it. I have seen some people say it it doesn't keep it fully charged and have had it go dead.

     

    As I said, I just hoped it would maintain the charge for me (or perhaps charge overnight with the MB Pro off).

     

    I have read that different adaptors have slightly different output voltages.

     

    Plus, Apple makes the 27 inch displace with MagSafe charger and it's supposed to charge all models, right?

     

    That said: There desn't seem to be a distinction when purchasing replacement adaptors.

     

    I also noticed my MB Pro from this year didn't have the right-angle MagSafe connector, I thought

     

     

    On the other hand:

    I see that on http://support.apple.com/kb/HT2346 and this is kind of odd in my opinion.

    Apple says:

    Note: 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

     

    This one really surprised me that Apple says there are differences between MacBook Air model chargers!?!  Or are they just saying the connectors are more flimsy or something (maybe they recalled those).  This seems really strange, especially when you consider how small (and gray) they make the print on these. How can you tell the difference if they aren't labeled well.

     

    Gary

  • 11. Re: Will my MacBook Pro charging cord safely work to charge my MacBook Air -- and vice versa?
    Csound1 Level 8 Level 8 (35,470 points)

    You can use the MBP charger with the Air without issue, using the MBA charger with the Pro will work but the charger is incapable of charging the MBP while it is running (not enough power available) it will run, and it will charge it but only if you switch off.

     

    Take the MBP charger, that way you can charge either machine.

  • 12. Re: Will my MacBook Pro charging cord safely work to charge my MacBook Air -- and vice versa?
    Courcoul Level 6 Level 6 (11,470 points)

    Those older (<= 2008) power bricks came with a MagSafe T-connector, in contrast to nowaday's L-connectors. Never having  ripped one open, can't imagine what overwhelming difference may lay inside, but Apple even had to put out a firmware patch when the L-connectors came out so the older Macs could use them. But as even our Certified Electrician has pointed out, since both have L's, you'll be fine using the big'un on the little'un.

     

    Woe befall you should you drink the Retina koolaid; those things have a different and incompatible MagSafe 2 power brick that returns to the T-connector formfactor (and requires an adapter to use a regular powerbrick, $20)

  • 13. Re: Will my MacBook Pro charging cord safely work to charge my MacBook Air -- and vice versa?
    garylapointe Level 1 Level 1 (20 points)

    My MacBook Pro 13 inch mid-2012 still came with an MagSafe (1) but went back to the T-connector.

     

    Gary

  • 14. Re: Will my MacBook Pro charging cord safely work to charge my MacBook Air -- and vice versa?
    garylapointe Level 1 Level 1 (20 points)

    But the MBP charger is a lot heftier and 9 out of 10 times I don't need a charger.  That's why I started looking for an answer to this.  I just want to carry the smaller charger.   

     

    I'd prefer not to carry a charger at all, but sometimes things happen and since I can't carry a spare battery, I need a charger.

     

    Gary

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