MagSafe 60W vs MagSafe 85

Discussion in 'MacBook Pro' started by enucho, May 8, 2011.

  1. enucho macrumors newbie

    Feb 20, 2008
    Hi there,

    I just bought a 15" MacBook Pro. At first I wa really happy to see that the MagSafe connector fit. Amazing, for Apple, I thought. But then, I discovered that my older MagSafes have a different wattage.

    I have two 60W. My hope is that I could have one permanently at school, one permanently at home and the third for when I travel around making presentations.

    So, my question is: how harmful to the new unit would it be using a 60W MagSafe?

    Thanks much,

  2. GGJstudios macrumors Westmere


    May 16, 2008
    No, not harmful. It may take longer to charge, but won't hurt anything.
  3. gnasher729 macrumors P6


    Nov 25, 2005
    Not to the MacBook, but to the charger. Chargers get hot. The 60 watt charger is designed to handle the heat from a device pulling 60 watt, the 85 watt charger is designed to handle the heat from a stronger device pulling 85 watt.

    Using a fully charged MacBook with the charger or charging a MacBook that isn't turned on should be safe. If you charge the MacBook while using it, it will pull more power than the charger will like.
  4. NickZac macrumors 68000


    Dec 11, 2010
    As noted, the heat may be problematic. I would not do it given it was not designed for this.
  5. enucho thread starter macrumors newbie

    Feb 20, 2008
    Using MagSafe 60 on a Mac Pro that came with a MagSafe 85

    Many thanks for your answers, info and advice. I will take them into consideration.

    My desire to use a 60W device is for simple convenience when necessary. I will make sure the battery is fully loaded before I connect a 60W device.

    Thanks again.

  6. Jhingha macrumors regular


    Feb 28, 2011
    If it wasn't designed for your new mpb. apple would have figured something out for that, a constrain so it wouldnt fit.

    it gets hotter, but it won't melt or anything
  7. enucho thread starter macrumors newbie

    Feb 20, 2008

    well, i finally tried it. And the person who said better not (at least in my case) is the winner: Yes, the 60w charger did heat up, but i wa amazed at how quicly and intensely the macbook pro heated up. It was almost scary. T heated up right below the left side of the screen.

    Thanks for all of your contributions.

  8. m85476585 macrumors 65816

    Feb 26, 2008
    A 60W magsafe means that it can supply up to 60W. If you plug it into a 15" MBP that can draw up to 85W, the Magsafe identifies itself to the MBP, so the MBP will only draw 60W. The charger will be running at its full capacity, but it is designed for that. It will get hot, but it is designed for that. There is no combination of Macs and Magsafes that will cause an unsafe situation if everything is working normally. Even if something along the way malfunctions (very unlikely), there are safety systems in the MBP and the Magsafe (temperature sensors, current limits) that usually prevent damage. If they weren't meant to work together, the connectors wouldn't fit, or it would simply refuse to work.

    I'm surprised the MBP heated up more than normal using the 60W charger. That doesn't really make sense, even if it is working normally.
  9. dagamer34 macrumors 65816


    May 1, 2007
    Houston, TX
    You'll get a worse problem than you realize. Since the MacBook Pro is expecting 85W and only getting 60W, at full load, your computer is going to be using both AC power to charge the battery as well as attempt to run off of AC as well. It's not going to be able to do both. And sicne it can't cope, it'll be drawing power from your battery, effectively draining it (though at a slower rate than no AC at all). You'll essentially be putting extra stress and charge cycles on the battery should you decide to do this full time.

    Using a 60W charger while your MBP isn't in use is fine, but I think using and charging at the same time will spell trouble for your laptop and it's battery.

    *Also, charging your battery generates some heat*
  10. jlc1978 macrumors 68020


    Aug 14, 2009
    Works fine - I've been doing that for nearly a year with no problems. My 60W charger is a little slower charging but doesn't run hot at all. The MBP simply gets less current from the 60 than the 85.

    As fro your heating problems, I've never had that issue. I'd go to an Apple store and check it out. There is no reason for your machine to exhibit that behavior simply because of the charger's power capacity.
  11. sebgreen macrumors regular

    Mar 25, 2008
    Wirelessly posted (Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_3_3 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8J2 Safari/6533.18.5)

    I have asked apple this very question. Their answer was DO NOT USE a 60watt charger for a 15inch MVP. It needs an 85watt.

    Damage will be done to the machine and the charger. It's like running any electrical device off the wrong wattage. Just don't do it.

    It's fine to use an 85watt charger with a 13inch mbp or mb as the charger will only supply the wattage that is needed, so 60watts, but the 60watt can not provide 85watts.
  12. 8CoreWhore macrumors 68020


    Jan 17, 2008
    Big D
  13. Macsavvytech macrumors 6502a


    May 25, 2010
    If you look at the product page they "recommend" the 60W for 13" and smaller laptops and the 85W for 15" and bigger. the key word is recommend the 60W will simply take longer to charge a 15" or 17" MBP.
  14. DustinT macrumors 68000


    Feb 26, 2011
    Apple engineered these to not cause problems. If it was going to cause problems there would be a different connector on it. Don't worry.
  15. Tibits macrumors 6502

    Feb 23, 2011
  16. alphaod macrumors Core


    Feb 9, 2008
    If you use your laptop at full power (ie: CPU 100%, etc.), you could see your battery being discharged even if you're plugged into an adapter. The 60W adapter will be more than likely to be unable to supply enough power in these situations.
  17. bniu macrumors 6502a

    Mar 21, 2010
    any magsafe charger will charge a macbook, air, or pro. Not necessarily 100% efficiency, but it'll work.

    There's 3 of the chargers: 45W, 60W, 85W
    3 Macbook groups: MacBook Air (Group A), macbook/macbook pros with integrated graphics, this includes the 2009 15" MBP that sold for $1699 (Group B), macbook pros with discrete graphics (Group C).

    85W will charge all three groups at 100% efficiency. If you are buying spare chargers to leave plugged in all the time, this is the one to buy. No matter what you plug into it, it'll charge it and charge it well.

    60W will charge Groups A and B at 100% efficiency, it'll work with Group C but with reduced performance. The only advantage to the 60W is it won't trip an airplane's power port.

    45W will charge Group A at 100% efficiency, it will work with Groups B and C with reduced performance.

    All my iOS chargers are the 10W variety used for the iPad, so I don't have to constantly think if a certain charger is iPad worthy. When it charges an iPhone, it just outputs 5W instead. All my spare mac chargers are 85W, it's just much easier this way.
  18. jlc1978 macrumors 68020


    Aug 14, 2009
    What damages electrical device is improper voltage, frequency, polarity, etc; not Wattage.

    Wattage is a measure of power; i.e. the load carrying capacity of the power supply.

    Given the two Apple PS in question have the proper connector and voltage; the only question is can the PS handle the load. The answer to that is yes, with some reduced charging ability.
  19. GGJstudios macrumors Westmere


    May 16, 2008
    Completely false.

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