6 Replies Latest reply: Dec 30, 2008 1:15 PM by maclover009
AKThom Level 1 (15 points)
Is there any reason why I can't use the 85W charging unit for a MacBook? I know it comes with the 60W version. Would the larger unit overheat the battery? I want to buy a second Magsafe charging unit to keep at the office and since they are both the same price would like to know if I would cause any damage by using the larger unit.

Also, noticing comments in another topic talking about battery cycles, isn't it bad to leave a computer on the charger 98% of the time? Shouldn't it be disconnected once the battery is fully charged? Is there circuitry that protects the battery if it's left on charge?

MacBook 2.4 (Alum), iPod Touch, iPod Shuffle, iPhone 3G, Mac OS X (10.5.6), HP Pavilion, Vista 64-bit, Quad core, 8gb RAM, 4tb desktop storage
  • Kappy Level 10 (265,888 points)
    Both chargers will work. There is no problem leaving the computer connected to the AC adaptor. It does not affect the battery's life. The charging circuitry shuts off once the battery is charged and will not turn on until the charge level drops below 95%.
  • maclover009 Level 1 (65 points)
    Don't mean to correct but the new MacBook's won't charge unless it is less then 93%. It is changed in the latest version of the SMC Update.

    Just to be advised,

    - Harris
  • Robert McDougall Level 1 (5 points)
    I sorta have the opposite question.

    A friend and I both have Late 2008 Macbooks - but I have the Pro. I was using his 60W charger with no problems, except it was a little slow to charge - but I just needed a little top up.

    I then switched to Vista to play Crysis and after about 30 minutes, between levels there was some silence and I heard a strange squeaking noise coming from the 60W adapter.

    Needless to say I immediately unplugged it.

    This then led to an interesting series of tests where we established that that on a scale of lots of noise to no noise, the 60W adapter behaved as follows:

    Vista on MBP (Lots of noise)
    Mac OS X on MBP (Some noise)
    Vista on MB (less noise)
    Mac OS X on MB (no noise)

    This is a little disturbing... For now I will only be using 85W adapters with my MBP, but what about vista on his MB? Could he fry his adapter?
  • Kappy Level 10 (265,888 points)
    Thanks for that update.
  • Kappy Level 10 (265,888 points)
    You should not use the 60 W adaptor on a MBP. You will most likely burn out the adaptor if you use it while the computer is active. It's sufficient to charge the battery while the computer is turned off, but it is not adequate for when the computer is active.
  • maclover009 Level 1 (65 points)
    Yes Kappy is right... The original question asks if it okay to use the 85w adapter on the MB. That is okay because the MacBook can regulate the intake of power.

    On the other hand, using the 60w on the MBP is NOT okay. The MacBook Pro tries to take more power then the 60w can provide and it is like putting to many things on a household circut. It will blow a fuse. But in this case it will overheat the 60w power adapter causing it to burn out.

    The best thing to do really is to use the provided power adapters for each computer. If you are in a sticky situation it is acceptable to use the 85w on the MacBook but never the 60w on the Pro.

    And lastly the 85w power adapter will not charge the MB any more because the MacBook regulates the voltage intake and its MagSafe board will not take any more voltage then the 60w power adapter can provide.

    - Harris