New MB... Are My Old Chargers Useless

Discussion in 'MacBook Pro' started by oo7ml, May 28, 2015.

  1. oo7ml macrumors 6502

    Jan 20, 2010
    Hi, i've just got a new MB.

    My old MB is 4 years old and i've managed to build up 3 chargers (work, home, travel bag) for it over the last few years.

    My Old MB uses: 85W Magsafe Power Adaptor

    My New MB uses: 45W Magsafe 2 Power Adaptor

    Can i use my old 85W Magsafe Power Adaptor on my new MB or will it harm the battery?
  2. Richdmoore macrumors 68000


    Jul 24, 2007
    Troutdale, OR
    Apple makes a MagSafe to MagSafe 2 adapter for just this purpose. You are also good using a higher power source 85w with a smaller drawing computer (your 45w new computer).

    My wife uses an older 60w MacBook adapter with the converter for her newer MacBook Air.

    One final thing I would recommend is something called a magcozy. I purchased one on Amazon, it is a leash that keeps the converter firmly attached to the power cord (also useful if you frequently switch back and fourth between MagSafe one & MagSafe 2 computers frequently.
  3. simonsi macrumors 601


    Jan 3, 2014
    In my experience they all work with all Macs, the device will draw what it needs up to the limit of what the charger can give. Big machines can end up charging very slowly or not at all on the small chargers, small devices charge quickly on the big devices but the Mac won't allow overcharging as far as I can tell.
  4. maflynn Moderator


    Staff Member

    May 3, 2009
    I use an older Magsafe with my newer magsafe 2 computer. The older Magsafe connector is coming from my Apple Cinema Display, but I think its the same thing. As simonsi posted, the computer will take only what it needs :)
  5. Chundles macrumors G4


    Jul 4, 2005
    MacBook: No, it uses a USB-C charger.

    MacBook Pro, MacBook Air: Yes, with an adapter. It won't harm the battery.

    If you have a 45W MagSafe 2 then you have a MacBook Air, not a MacBook as you said.
  6. snaky69 macrumors 603

    Mar 14, 2008
    It's impossible to harm the battery that way. The power adapter does not push power into the computer. Rather the computer draws power from it.

    The computer'll draw what it needs, no more. You could plug it in straight into the Hoover dam if you liked, it'd still only draw what it needs.

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5 May 28, 2015