Can I use 85W MBP adapter for my Macbook?

Posted:
in General Discussion edited January 2014
An acquaintance said, it is OK to use 85W MBP adapter for Macbook, though, the opposite isn't OK.



I'm considering buying 85W instead of 60W even though I have a Macbook, because I'm going to buy a Macbook Pro someday, in a year, then I will be able to use two 85W adapters.

Comments

  • Reply 1 of 12
    nvidia2008nvidia2008 Posts: 9,262member
    They are more or less interchangeable, actually. However, for warranty, peace-of-mind, etc. etc. stick to 60W for MacBook and 85W for MacBook Pro.



    Respect the authoritaaaaa!!!
  • Reply 2 of 12
    dentondenton Posts: 725member
    Quote:
    Originally Posted by Netimoon View Post


    An acquaintance said, it is OK to use 85W MBP adapter for Macbook, though, the opposite isn't OK.



    I'm considering buying 85W instead of 60W even though I have a Macbook, because I'm going to buy a Macbook Pro someday, in a year, then I will be able to use two 85W adapters.



    nvidia is probably right about interchangeability, however, I think your acquaintance has the wrong intuition. Supplying more power to a device that is not designed to handle it could fry the device (using an 85W power supply for a notebook that is designed to accept a 60W input is bad). The worst that can happen if you do the reverse is that your device won't run (supplying a MBP with 60W may cause it to use battery power rather than power supplied through the adapter). Someone will have to correct me if the above is wrong.



    Get a 60W adapter for the Macbook and an 85W adapter for the MBP. But if you think that saving $80 is worth frying your $1500 computer after one year, feel free. However, as nvidia said, this is probably not going to happen: but why take the chance?
  • Reply 3 of 12
    john.bjohn.b Posts: 2,717member
    Quote:
    Originally Posted by Denton View Post


    Supplying more power to a device that is not designed to handle it could fry the device (using an 85W power supply for a notebook that is designed to accept a 60W input is bad).



    If the Macbook is a 60W device I don't believe the it would pull more than 60W, even from an 85W power supply. Assuming the voltages between the two adapters is the same, and that they have similar voltage regulators.



    Quote:
    Originally Posted by Denton View Post


    Get a 60W adapter for the Macbook and an 85W adapter for the MBP.



    Probably the best advice, short of getting Apple support to confirm the 85W PS is compatible with the Macbook.
  • Reply 4 of 12
    mcarlingmcarling Posts: 1,106member
    They both use the same voltage, so there is no possibility of frying the device. It's just extra weight to carry around.



    It's also fine to use a 60W power supply with the MacBook Pro. The only problem is that it will not charge the battery while you're using the laptop. If it's plugged in and you're using it, it will take power from the adaptor to run the laptop, but will not charge the battery. It will charge the battery only when the laptop is sleeping or powered off.
  • Reply 5 of 12
    e1618978e1618978 Posts: 6,074member
    The 85watt adapter will work with the macbook or macbook pro. The 60W will only work with the macbook. My daughter uses an 85 watt adapter on her macbook and it works fine.



    I can't find it now, but I think that the macbook and macbook pro actually use different voltages from the power adapter, and the 85W one auto-senses what you need and sets the right voltage.
  • Reply 6 of 12
    If the DC voltage output of the 85W brick is close to the output of the 60W brick (within 2V or so) you'll be fine.
  • Reply 7 of 12
    Quote:
    Originally Posted by e1618978 View Post


    ...... The 60W will only work with the macbook. My daughter uses an 85 watt adapter on her macbook and it works fine......





    Not true. My wife has a MB and I have a MBP. I leave my 85 watt brick at work and use her 60 watt brick when I get home "every" night.



    It will not charge the battery while I use it, but will supply constant power and the battery never drains. When I close it, I leave it plugged in and its fully charged when I wake up.
  • Reply 8 of 12
    Switching power supplies regulate best in the upper half of their range. Pulling 40 watts from an 85 watt power supply may give you some ripple. That said, we have a gigantic capacitor in our Macs (called a "battery" ) that smooths any lows out pretty well, and all the internal voltages are supplied by internal voltage regulators that chop out the ripple before it can get to internal components. As long as it charges (i.e., the low parts of the ripple don't fall below the gate voltage of the charging circuit), you aren't harming your Macbook.



    Oh, why you may want to get the 85 watt supply for your Macbook as your extra power supply -- the 60W supply gets *hot* when the Macbook is under load, and the battery charges extremely slowly. It's clear to me at least that the 60W supply is pretty marginal for the Macbook when it's chugging both CPU's hard and playing a DVD too, not only do you have the howling fan, but the power cube gets so hot that it becomes hard to pick up. So if you really push your Macbook hard, as vs. just use it for web browsing and word processing, the 85w may provide some "peace of mind" that your power supply isn't going to melt through the top of your computer desk .
  • Reply 9 of 12
    maussemausse Posts: 14member
    Quote:
    Originally Posted by badtux View Post


    Switching power supplies regulate best in the upper half of their range. Pulling 40 watts from an 85 watt power supply may give you some ripple. That said, we have a gigantic capacitor in our Macs (called a "battery" ) that smooths any lows out pretty well, and all the internal voltages are supplied by internal voltage regulators that chop out the ripple before it can get to internal components. As long as it charges (i.e., the low parts of the ripple don't fall below the gate voltage of the charging circuit), you aren't harming your Macbook.



    Oh, why you may want to get the 85 watt supply for your Macbook as your extra power supply -- the 60W supply gets *hot* when the Macbook is under load, and the battery charges extremely slowly. It's clear to me at least that the 60W supply is pretty marginal for the Macbook when it's chugging both CPU's hard and playing a DVD too, not only do you have the howling fan, but the power cube gets so hot that it becomes hard to pick up. So if you really push your Macbook hard, as vs. just use it for web browsing and word processing, the 85w may provide some "peace of mind" that your power supply isn't going to melt through the top of your computer desk .



    thanx a million, very usefull advice!
  • Reply 10 of 12
    nvidia2008nvidia2008 Posts: 9,262member
    Quote:
    Originally Posted by nvidia2008 View Post


    They are more or less interchangeable, actually. However, for warranty, peace-of-mind, etc. etc. stick to 60W for MacBook and 85W for MacBook Pro.



    Respect the authoritaaaaa!!!



    Wow. I totally forgot I made this comment.
  • Reply 11 of 12
    The new cinema displays feature a built in power adapter for your "macbook" however I expect a lot of Macbook Pro users would want them also. I asked in a local store and they said it would work fine on either but I don't know how savvy the sales guy was. Anyone know if these 60 or 85 watts? If they supply 85 watts and they're recommending them for macbooks then I'm sure the normal MBP adapter is fine too.



    http://www.apple.com/displays/features.html
  • Reply 12 of 12
    e1618978e1618978 Posts: 6,074member
    From the tech specs:

    "Maximum power: 212W (LED Cinema Display while charging MacBook Pro"



    so yes, the monitor can charge the macbook pro.
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