What happens if you use a MacBook Pro Power supply on a MacBook?

Discussion in 'Mac Basics and Help' started by BiikeMike, Jul 8, 2006.

  1. BiikeMike macrumors 65816

    BiikeMike

    Joined:
    Sep 17, 2005
    #1
    My girlfriend just got a MacBook a few days ago, her battery was lasting 4 hours out of the box, and when I got home today, she asked me why her battery wasn't lasting long anymore.

    I told her I have no idea, and then when she went to charge it, she used my charger for my MBP. I told her not to do that because its more powerful, but I actually don't know if that affects it or not....... does it?
     
  2. mad jew Moderator emeritus

    mad jew

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    Location:
    Adelaide, Australia
    #2
    I would've thought the adaptor would automatically drop back to 60W and work perfectly but apparently not. Tell her to use her own charger and see if she gets a better life. Maybe also tell her to calibrate her battery quickly. :)
     
  3. BiikeMike thread starter macrumors 65816

    BiikeMike

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    Sep 17, 2005
    #3
    Thats funny, thats EXACTLY what I did.

    She said "whats calibrating a battery?." I just told her to stop using my charger and let her battery run out, then dont touch her computer until tomorrow ;)
     
  4. mad jew Moderator emeritus

    mad jew

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    #4
    Cool. I'd be interested to hear if it makes a difference (the new charger). :)
     
  5. mjstew33 macrumors 601

    mjstew33

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    #5
    I would NOT let her use it!

    The voltage is probably higher therefor making it VERY applicable for problems.

    I don't know the specs, but... MacBook -> MacBook Pro, just like the iBook to PowerBook, I bet they have a bit of a different voltage.
     
  6. BiikeMike thread starter macrumors 65816

    BiikeMike

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    Sep 17, 2005
    #6
    the MBP is 85w, and the MB is 60w.
     
  7. BiikeMike thread starter macrumors 65816

    BiikeMike

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    Sep 17, 2005
    #7
    and oh yeah.... I didn't LET her use it, if I knew that she was gonna use it, I woulda told her not to. ;)
     
  8. dmw007 macrumors G4

    dmw007

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    #8
    I have heard of people using a MacBook power adapter with their MacBook Pro. But not vice-versa. I suppose going with a lower power adapter would be okay (as in the case of the MBP us a MB adapter) but I don't think that I would want to take the risk and use a MacBook Pro's power adapter with a MacBook. :eek: :)


    But go ahead and do it if you would like a roasted MacBook. :p ;)
     
  9. mduser63 macrumors 68040

    mduser63

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    Nov 9, 2004
    Location:
    Salt Lake City, UT
    #9
    The wattage rating tells how much maximum current (in terms of power since the voltage is known) the adapter can supply. Using a higher wattage adapter shouldn't cause a problem since the Mac has smart charging circuitry inside.

    Confirming this, the August 2006 issue of Macworld (middle of page 16) specifically states that Apple told them that a MacBook Pro charger will work fine on a MacBook. A MacBook charger will also work fine on a MBP, but it's probably not powerful enough to charge the battery while the computer is being used for heavy-duty stuff.
     
  10. yankeefan24 macrumors 65816

    yankeefan24

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    #10
    Exactly what Apple told me. I have been using a MBP charger at my desk for my MB since day 1. That was the Saturday they came out. My computer is fine.
     
  11. dmw007 macrumors G4

    dmw007

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    #11

    There you go BiikeMike, you can safely use your MacBook Pro's power adapter on your girlfriend's MacBook. :)
     
  12. BiikeMike thread starter macrumors 65816

    BiikeMike

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    Sep 17, 2005
    #12

    Thanks everyone, you guys rule :D
     
  13. mad jew Moderator emeritus

    mad jew

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    #13

    That's exactly what I thought but it's really only theoretical. There's a slim chance it won't work in practice, hence the problems of BiikeMike. I'd still try calibrating and using the appropriate battery. Then, once it's working normally again feel free to test whether she can go back to using your charger. :)
     
  14. mjstew33 macrumors 601

    mjstew33

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    #14
    That is very interesting - I wasn't sure or not, but that's really cool that you can do that. :)
     
  15. godspeed macrumors member

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    Apr 8, 2006
    #15
    I was using my macbook power supply on my macbook pro........... that was until my macbook pro battery decided not to hold a charge anymore. Basically I think the underpowered supply screwed the calibration of the battery. Apple gave me a new one for free, but from now on I am charging each laptop from their respective power supplies.
     
  16. OutThere macrumors 603

    OutThere

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    #16
    Same with Powerbooks/iBooks.

    If Apple were to make a power adapter with a different voltage, it wouldn't plug into the same plugs.
     
  17. Makosuke macrumors 603

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    Aug 15, 2001
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    The Cool Part of CA, USA
    #17
    Same voltage = fine, as long as it can supply enough current. MBP and MB power supplies (so far as I know--I've only looked at a MPB brick) supply 18.5V and 16.5V on the two sets of pins. You can look at the little text on your MB supply and confirm that.

    Assuming they're the same (and again, Apple would've made different connectors if they weren't), think of it this way: if overvoltage because the MB wasn't drawing enough juice was an issue, the the MBP would have the same issue when you were running it with, say, the HD asleep and the brightness on the screen turned way down. I'm quite sure it's easy to cause a MBP to draw less power than a MB for an extended period of time, depending on settings.

    That said, I know for a fact my 17" MBP really does need the 85W supply--it can draw a LOT of juice under heavy load. Although it would run off of the 60W MB supply, it definitely wouldn't be able to charge the battery while under load, and I would be seriously worried about it overheating the brick--the one that was designed for it already gets VERY hot, so I wouldn't trust what it would do to a 60W brick.
     
  18. jeremy.king macrumors 603

    jeremy.king

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    #18
    Being an owner of both. Take a closer look at the MBP power supply. Its interestingly rated at 18.5V - 4.6A (MBP power level) AND 16.5V - 3.6A (MB power level).
     
  19. TheMonarch macrumors 65816

    TheMonarch

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    May 6, 2005
    Location:
    Bay Area
    #19
    Just to simplify things a bit:

    85W charger on a MacBook = Fine. It auto-detects, and works.

    60W charger on a MacBook Pro = Fine*

    *Under certain conditions (Heavy load) it will automatically switch to the battery for extra power (Therefore drain it). It will also charge more slowly, and WILL NOT harm the charger, as it will never supply more power than it is rated for.


    Same applies to all PowerBook G4s.


    :)
     
  20. thomanjones macrumors regular

    Joined:
    Dec 26, 2006
    Location:
    DC
    #20
    An advantage to using a 60w MB adaptor with a MBP is for airline power - many aircraft seat A/C connections max out at 75w - too low for the 85w MBP adaptor. Saves some headache of unplugging/replugging to reset the circuit breaker.
     
  21. gusious macrumors 65816

    gusious

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    Dec 2, 2007
    Location:
    Greece
    #21
    Can i ask you something about calibration?

    I have a 17 MBP. So one the article(step 5 to 6):do i leave it for 5 hours without the adapter being plugged in and then i plug it until the battery gets full or do i plug the MBP with the adapter but also let it to rest for 5 hours when it is in sleep mode?

    Thanks!
     

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