Can I use a MBP Power adapter for a normal MB?

Discussion in 'MacBook Pro' started by kingping14, Apr 10, 2010.

  1. kingping14 macrumors member

    Apr 10, 2010
    I accidentally packed the wrong power adapter for my trip! I took the power adapter for my 17" MBP instead of the power adapter for my small MB. Will using a MPB's charger fry my MB?

    thanks in advance
  2. alphaod macrumors Core


    Feb 9, 2008
    Yes the 85W adapter is autosensing which means it will know it's charging a MacBook and send only 60W.

    For this reason, when you buy a replacement adapter, you can just buy MacBook Pro 85W adapter to use on a MacBook.

    However do the clearance issues on the MacBook Air, using the same adapter on the MacBook Air is impractical.
  3. hamlinspahn macrumors regular

    Apr 9, 2010
    Oklahoma City

    No it will not matter. If you go to an Apple store to buy a new one for your MB you will get the one that ships with the MBP.
  4. kingping14 thread starter macrumors member

    Apr 10, 2010
  5. LeeTom macrumors 68000


    May 31, 2004
    I'd just like to back up what everyone else is saying, and add that the opposite is not true: you cannot use a 60W MacBook power adapter to charge an 85W MacBook Pro. It doesn't provide enough juice!
  6. iThinkergoiMac macrumors 68030

    Jan 20, 2010
    What you're saying is correct, but the mechanics you're describing are not. The wattage rating on a power adaptor is describing the maximum wattage that can be drawn. It will not always send that amount of wattage. The amount of wattage it sends is determined by the computer. So if your computer needs 72 watts of power for whatever task it is doing, it will attempt to draw that much power. If your adaptor can produce 72W or more, everything is fine and dandy. If not, it'll burn out the adaptor by over-drawing wattage. An 85W adaptor does not send out 85W constantly, it's just capable of sending out a maximum of 85W if needed.

    Thus the adaptor is not sensing what kind of computer is attached. It's not actually capable of that. The MB is simply not going to draw more than 60W, and it will only draw what it needs. Theoretically, you could put a 250W adaptor on it and, as long as it was the right voltage, you wouldn't harm anything. We do this kind of thing a lot at work, where customers come in to get replacement power adaptors for some kind of device and we match up the voltage and get the wattage as close as possible, but it's usually higher than what the device calls for.

    I think you may be thinking of auto-switching, which allows the adaptor to be used with voltage anywhere between 110 and 220 volts.

Share This Page