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NewbieCanada

macrumors 68030
Original poster
Oct 9, 2007
2,574
38
I bought a second adaptor for my old MBA, to have one for home and one for work. I sold the MBA but kept the extra adaptor.

Will it work on a new MBP (with the Magsafe 2 adaptor?) despite being 45 watt? I don't care if it charges more slowly, I'm just concerned about maintaining power, but I don't want to risk any damage.
 
It will work, but it'll kill the adaptor very quickly, the adaptor will get extremely hot and chances are even the slightest load on the MBP means it will use more power than the MBA charger can even provide, so it will ALSO use the battery power too - therefore not even charging it.

Don't use it in other words, unless its a definite last resort.
 
You need a $10 adapter. It'll charge fine, just very slowly or not at all under load. I've done it for years - no problems.
 
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