What happens when I use a 45w Air power Adapter on my MacBook?

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Level 2

245 points

What happens when I use a 45w Air power Adapter on my MacBook?

Thru an excess of travel, I'm separated from the 60W adapter that powers my MacBook for a few days. I do have a spare 45W Adapter for an Air, which plugs in and the green light comes on. The MB says "Not Charging" in the battery status if it's on but it doesn't say "Abort, Abort, Danger Will Robinson" or any thing dire. Of course I can't tell if it is or isn't charging while in Sleep except by waiting a while. I will be reunited with the proper adapter in a few days, so I'd rather not buy a replacement. Can anyone comment on the potential for this unusual union? Seems like I can't be the first guy in this situation?

Will 45W adapter charge the battery while sleeping? Is there enough power to run the MB but not enough additional to charge while running (I can live with that)? Is the union likely to have a bad outcome?

Thanks!

MacBook 2.0GHz Core 2 Duo, Mac OS X (10.6.8), MB Air, iPhone 3g, AEBS Gig, 3G ipod, Windows-free home since 19

Posted on Jun 15, 2012 5:42 PM

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Answer 1

Jun 15, 2012 5:51 PM in response to Michael King

There will not be enough power to run the MB, but if the MB is shutdown and then the charger attached it may charge though very slowly. Most advice is you can use a more powerful charger but not less powerful. If you don't see any increase in battery charge then it is not charging.

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Answer 2

Michael King Author

Level 2

245 points

Jun 16, 2012 11:14 PM in response to Michael King

For those interested, after 24 hours of experimentation with this situation...

Ralph's answer isn't entirely correct - the 45W adapter does provide enough power to run the computer, although I suspect the computer might be running at a reduced performance level. Email and web browsing were tested most, and some graphics intensive video & one game.

If left in Sleep mode, the battery does charge, but very, very, very slowly. I have not seen any undesirable effects of this, other than the above. Seems to be okay for an emergency like I have, but doens't seem to be okay for a longer term.

Thanks!

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