5 Replies Latest reply: Feb 15, 2010 2:34 PM by Rod Hagen
collegegirl Level 1 Level 1 (0 points)
Hi, it is finals time and my 85W Macbook Pro charger has just decided to quit on me. My friend is selling her 60W charger that she uses on her 13 inch Macbook Pro...can I buy it and use it on my 15 inch one?

Thanks!

MacBook Pro, Mac OS X (10.4.11)
  • iVmichael Level 6 Level 6 (13,725 points)
    It's best you get the 85W model for your MacBook Pro, that one might charge the battery when the MBP isn't in use but in normal operation it could be problematic.

  • Niel Level 10 Level 10 (278,405 points)
    can I buy it and use it on my 15 inch one?


    Yes. The 60 watt charger may take longer to charge your computer, and in times of high power usage, may not charge the battery.

    (49138)
  • tritoniadiomedea Level 2 Level 2 (385 points)
    Keep in mind that brand new MBPro 15" 2.53 GHz machines come with the 60W adapter, so Apple seems to be recommending that for the slower MBP model. So the answer probably depends on how much power the machine draws, which is a function of how much RAM you have and your usage.
  • Rod Hagen Level 7 Level 7 (31,985 points)
    Hi collegegirl,

    The earlier MBPs, like yours, have a separate Graphics Processing Unit that adds to the power draw when compared with the current "base model" 15" 2.53 model that comes with the 60W power supply. The newer computers also have a reduced power load in other areas, too.

    I've run my own older SantaRosa 15" on 60W power adaptors on various occasions (more by accident than deliberate decision - we have several of both varieties in the house) and nothing untoward has happened, but they are likely to heat up a little more than an 85W when used on an "85W" computer, and your battery may also be "called on" to supply extra power on occasion, even when the charger is connected.

    http://support.apple.com/kb/HT2346 has some advice, and lists the adaptors appropriate for different MBPs.

    So, in short, though the solution probably seems appealing to you both, it is not really a good idea, I'm afraid.

    Cheers

    Rod
  • Rod Hagen Level 7 Level 7 (31,985 points)
    Hi tritoniadomedea,

    The big difference between the current 2.53 model (that comes with the 60W adaptor) and both the older MBPs and the current "higher spec" ones, is not RAM level. It is the presence of a separate GPU in the models that come with 85W adaptors.

    The 2.53 (like the MacBooks that also have used 60W adaptors and the 13" MBPs ) has an integrated graphics processor. This substantially reduces power demands.

    Cheers

    Rod