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65 watt power inverter to an 85 watt MagSafe?

Kingsly

Kingsly

macrumors 68040
Original poster
... Will something blow up or will it simply deliver 65 watts (no battery charge) to my MBP? I am going to Japan and would love some movies on the plane. 😉
 
I once connected a 65W adapter to my MBP and it worked fine.

But long term usage... nobody knows 😎

Power inverter may overheat and catch fire, but that's the worst I can think of. Any engineers on this thread?
 
I think the issue with the 65W one on an MBP is that it can't keep up with peak demand and so might not keep it charged. However, I've got a 65W one upstairs for my MB and have used it on occasion to charge (not while being used) my MBP, with no harmful effects.
 
The main thing I am wondering is if a 65watt inverter will:

A) deliver 65 watts and not a drop more, thus forcing my 85 watt magsafe to run on 65 watts, or B) reacts adversely to a stronger current draw than it is capable of, either bursting into flames or, preferably, shutting down.
 
jsw said:
I think the issue with the 65W one on an MBP is that it can't keep up with peak demand and so might not keep it charged. However, I've got a 65W one upstairs for my MB and have used it on occasion to charge (not while being used) my MBP, with no harmful effects.
Click to expand...


does it charge the macbook faster suing the 85w power supply than it normally does using the 65w
 
orangemacapple said:
does it charge the macbook faster suing the 85w power supply than it normally does using the 65w
Click to expand...
I haven't timed them, and so it might, but I didn't notice any particular difference (but, then again, I might not have - I tend to charge overnight). I do know that the 85W one is officially blessed for use on both, whereas the 65W one is officially just for the MB.
 
would you do that for me

jsw said:
I haven't timed them, and so it might, but I didn't notice any particular difference (but, then again, I might not have - I tend to charge overnight). I do know that the 85W one is officially blessed for use on both, whereas the 65W one is officially just for the MB.
Click to expand...

that would be something i'd really like to know. it might make it worth the $79 to charge it in half the time.
 
This was a common question pre-MagSafe too. Using a lower rated adapter/inverter/whatever will simply supply less than necessary, so it will take longer to charge than if the supplied adapter/whatever was used. I suppose that in cases of extreme power usage, it might need to use the battery a bit too.
 
85 w on my macbook

my cord for my macbook broke so i purchased the 85 w for the pro it will not charge my laptop in any way if i plug it in the led stays green but will never change and charge my laptop. why is it doing this do i need to change any settings?
 
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