MacBook Power Supply with MacBook Pro

Discussion in 'MacBook Pro' started by stevemolitor, Jun 26, 2007.

  1. stevemolitor macrumors newbie

    Joined:
    Apr 13, 2004
    #1
    I have a new mac book pro, with the bigger power supply. Can I safely use my old, smaller, mac book power supply with it? (I'd like to leave one power supply at work.)

    Steve
     
  2. iBookG4user macrumors 604

    iBookG4user

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    Location:
    Seattle, WA
    #2
    I've never done it, but I've heard that you can use it, although it will not charge the battery.
     
  3. Sbrocket macrumors 65816

    Sbrocket

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    #3
    You can safely use it; neither the power supply nor the computer is going to blow up because of it, rest assured. However, the MacBook power supply is designed to pull a lower current than the MacBook Pro's power supply (in terms of power (watts) instead of amps, the MacBook PS puts out 65W while the MacBook Pro PS puts out 80W). As a result, your MBP will charge...but much slower. Its safe to use and you're free to do so, but it simply won't charge your MBP as fast.

    Personally I'd recommend leaving your MB power supply at work since it will probably be plugged in constantly there and has longer to fully charge, whereas the MBP power supply can recharge your laptop quicker for when you're on the go. But that's just my opinion.
     
  4. basicfiend macrumors member

    Joined:
    Jun 13, 2007
    #4
    There was a thread on this just yesterday, but now I can't find it.

    Short answer: yes, nothing's going to blow up or melt.

    Long answer: MBP has a 75 watt power supply and MB has 65 watt. When you're using the MB power supply with the MBP, supply might not deliver enough power and MBP might have to go to its battery to make up the difference. Depending on usage, you'll probably sneak by (but not charge battery). If MBP is sleeping, then battery will charge with MB power supply.

    Edit: or what SRocket said.
     
  5. Mr R macrumors member

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    May 25, 2007
    Location:
    Glasgow, Scotland, UK
    #5
    Do you think its safe to leave the MacBook Pro powered all the time i.e. not the actual Macbook running permanently but just plugged in and charging the battery? I know this means that the green led is always on, but should this be ok?
     
  6. iBookG4user macrumors 604

    iBookG4user

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    #6
    Yeah, that should be fine. I leave my MacBook pro plugged in all the time and it hasn't suffered battery problems.
     
  7. Mr R macrumors member

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    May 25, 2007
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    Glasgow, Scotland, UK
    #7
    Great - thanks for info. I know the battery will never really discharge (very much), if at all - but I don't really have any intention of moving the machine around.
     
  8. marvin*1*2 macrumors member

    marvin*1*2

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    #8
    and vice versa?

    and how about vice versa, ie plug a mbp power adapter into a mb?
    will that cause a thermonuclear chainreaction?:eek:
     
  9. iW00t macrumors 68040

    iW00t

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    #9
    Nope, it will just overclock your MacBook automagically. I managed to turn my 2.16ghz MacBook into a 4.32ghz MacBook the other day doing just that.
     
  10. DoFoT9 macrumors P6

    DoFoT9

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    #10
    thats what that powersurge and bright light was the other day.... i was wondering what that was
     
  11. Kasper Winding macrumors member

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    Denmark
    #11
    Well that should not be a problem at all. Another thing is that the Macbook Pro powersupply looks like a white macbook suppy. You got this good looking silverbar laptop and then the power supply is white plastic. Bad design apple :)
     
  12. gnasher729 macrumors P6

    gnasher729

    Joined:
    Nov 25, 2005
    #12
    You can do this in an emergency, but don't do it all the time.

    The power supply will deliver as much power as the device connected wants. The MacBook power supply is not built to deliver that much power all the time, so it will get hotter than designed and wear out quicker than designed. It would be ok to run a fully charged MacBook Pro using the smaller power supply, or to charge it without running it, but you shouldn't charge it while it is running all the time.
     
  13. DoFoT9 macrumors P6

    DoFoT9

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    #13
    it would cut out id think.. like have some kind of trip. is the MB power upwards compatible neways?? i wouldnt think it would be able to do that
     
  14. dusanv macrumors 6502

    Joined:
    Mar 1, 2006
    #14
    The MBP power brick is 85W for a reason. Try charging the battery and playing a game (to max out consumption) on a 65W brick and you may run into problems .
     
  15. gazy1344 macrumors newbie

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    May 13, 2008
    Location:
    London
    #15
    Just a quick question related to this post.

    I have a brand new macbook pro and would like to know if i can leave it 24/7 connected to the main with the standard charger without damaging my battery?

    Thanks

    Gary

     
  16. kgeier82 macrumors 65816

    Joined:
    Feb 18, 2008
    #16
    way to bring back a 1yr old thread :)

    your batteries lifetime is ticking the minute its produced. It will not be the battery it was in 1yr's time, whether you use it or not.

    It will hold a charge for sure if you keep it constantly plugged in. I wouldnt worry about its usage. Just use it as you see fit. there is nothing you can do to prolong its life.
     
  17. MM07 macrumors 6502a

    Joined:
    Feb 10, 2008
    #17
    I purchased a 85w charger for my MacBook the other day. The lady at the Apple store said it will work fine. Now I'm set if I need to upgrade to a MBP. :D
     
  18. e12a macrumors 68000

    e12a

    Joined:
    Oct 28, 2006
    #18
    Why buy the 85w? the MBP comes with its own, unless you like to have 2 (it is convenient in ways).

    Its fine to leave the computer plugged in 24/7. Just dont expect to get great battery life without calibration.

    Referring back to the OP, it is NOT recommended to run a macbook charger with a macbook pro. The 85w MBP charger may not even provide enough power under load, which is why you need to keep the battery inside while plugged in. The battery acts as a buffer. The 65w will probably be barely enough to power the computer let alone charge the battery at the same time if put under load. plus the weaker charging can damage the battery.

    It is okay to go down (85w to Macbook ) but not the other way.
     
  19. alphaod macrumors Core

    alphaod

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    Location:
    NYC
    #19
    The MB PS is rated 60W. The MBP PS is rated 60W-85W.

    Yes you can use both interchangeably. Apple says you shouldn't use the MB adapter if your battery is dead.
     

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