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MagSafe quickie

N

noservice2001

macrumors regular
Original poster
May 7, 2006
151
0
808 State
dad has a MBP with the old 85W big magsafe adapters, i have a air with the weird tip 45W magsafe...

every now and then i charge my air with his 85W and everything seems fine.... is this safe? can he use a lower W one like the 60W for MB?

i want to buy him a more compact charger for travel.... but i also intend to use it sometimes.... should i get the 60W or 85W?
 
Lightbulbs that burn brightest, burn half as long.

I don't recommend using adaptors with unmatched wattage in any case. Buy him the 85W, and get yourself a spare air adaptor.

Yes, it's easy for me to send your money, but just think how much of it you'd lose if the Air pops.
 
i love having quickies :D anyway the 85w power brick is great, i've replaced it twice through AppleCare and now have a smaller one.
 
I have a mbp and I have to use my wife's mb charger sometimes (60w). It works fine, but the battery takes more time to charge. I'm not sure that trying to power a mbp with a 45w adaptor would work though, since I think it takes more than that to run the machine, let alone charge the battery.
 
Charging with a higher wattage adapter is going to lower the life of your battery considerably, could be a fire hazard, could damage your computer, and is generally a bad idea.

Charging with a lower wattage adapter is going to take longer and in some cases will never trip the battery charge circuit, meaning that it may power the computer, but not charge the battery at the same time.
 
I don't quite think I agree with the last post. You're telling us that the power adapter is responsible for charging the battery? That there is no power board inside the machine responsible for regulating the power from the power source and diverting it in whatever way it sees fit?


I would take all the advice in here with a grain of salt. Simply having more power available will not hurt the computer in any way. It has a controller inside that charges the battery according to whatever condition it is in. Think of it as the same way you think of your power supply in a tower PC. Sure, you can have an 850 watt psu, but you only use whatever you need.

But in any case, if you're so concerned over it, why not ask Apple, rather than listen to anyone here who had nothing to do with the actual engineering of the product (including myself).
 
mrwizardno2 said:
I don't quite think I agree with the last post. You're telling us that the power adapter is responsible for charging the battery? That there is no power board inside the machine responsible for regulating the power from the power source and diverting it in whatever way it sees fit?
Click to expand...

Of course the circuitry is in the computer. But it will react differently based on the wattage that is available. Do some reading on the airline power supply. empower can't charge the battery either due to low wattage.
 
MagSafe quickie

Apple states that you can use the 85W adapter with your Macbook. The out put adjusts to the Macbook requirements.

You can also use the 60W Macbook adapter with your MBP in a pinch but it takes longer to charge and I can't seem to find a definitive answer as to whether or not it will run the MBP and charge the battery at the same time. There are conflicting opinions on that. You may also burn out the 60W adapter if you are doing heavy processing like video rendering (at least that's what an Apple rep told me).
 
I can confirm that a 60w macbook adaptor will charge a first-gen 17" mbp. The time necessary for a charge from flat-line goes from under 2 hours to about 3 hours, though.
 
saltyzoo said:
Of course the circuitry is in the computer. But it will react differently based on the wattage that is available. Do some reading on the airline power supply. empower can't charge the battery either due to low wattage.
Click to expand...

Exactly. That's because less power is available than what is required. It doesn't say anytihng about MORE.

Same thing as having an undersized PSU in a PC. It becomes unstable and / or powers off.
 
mrwizardno2 said:
Exactly. That's because less power is available than what is required. It doesn't say anytihng about MORE.

Same thing as having an undersized PSU in a PC. It becomes unstable and / or powers off.
Click to expand...

I misread your post, I thought you were contesting the low power statement.

You could certainly overload a circuit though in any case, although Apple may have assured that none of their power supplies would do so.
 
I use an older, big 85W MBP power supply on my macbook daily with no issues. Haven't tried it on an Air since I don't own one.
 
mrwizardno2 said:
why not ask Apple, rather than listen to anyone here who had nothing to do with the actual engineering of the product (including myself).
Click to expand...

yeah, in past experience those n00bz know less than mac rumors forum users....

so the conclusion is that i could safely use the 85W charger on an 45w supposed to be air and it'll be fine.... due to the auto regulation
 
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