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Adapter Question: Can I share?

SD-B

SD-B

macrumors 6502
Original poster
Apr 1, 2009
399
14
Hi I have 2 Macbook Pros from roughly the same time. Perhaps 10 months apart

They are almost the same. One is a 2.4 and one is a 2.56. One has the adaptor that snaps in as if from the side, whereas the other adaptor just snaps straight in.

I assume you will know what i mean by that horrible description, LOL but w hat i am wondering is if the two can be used on each machine back and forth.
Must one only work on one and the other, only on that one, etc since they are basically the same macbook pros?
 
Yes that was what I meant.

I have 2 but they are different.
One looked exactly like the one u linked to but the other one isn't on its side as that one is. It just goes straight in in a squarish magnet.
Thats what I wasn't sure about.

Thanks
 
As long as the wattage from the transformer is the same and it fits your good to go
 
Look at the markings on the "brick" to see if they are the same watts, amps, etc.
 
NukeIT said:
As long as the wattage from the transformer is the same and it fits your good to go
Click to expand...

Wattage may not matter. Taken from http://support.apple.com/kb/HT2346?viewlocale=en_US&locale=en_US:

"Power adapters for Intel-based Apple notebooks are available in 45W, 60W, and 85W varieties. Although you should always use the proper wattage adapter for your Apple notebook, you can use an adapter of a higher wattage without issue.

For instance, if you have a MacBook (13-inch Late 2009) that normally uses a 60W adapter, you can also use an 85W adapter with that computer. You would not use a 45W adapter with that computer; it would not provide enough power for that MacBook."
 
jg321 said:
Wattage may not matter. Taken from http://support.apple.com/kb/HT2346?viewlocale=en_US&locale=en_US:

"Power adapters for Intel-based Apple notebooks are available in 45W, 60W, and 85W varieties. Although you should always use the proper wattage adapter for your Apple notebook, you can use an adapter of a higher wattage without issue.

For instance, if you have a MacBook (13-inch Late 2009) that normally uses a 60W adapter, you can also use an 85W adapter with that computer. You would not use a 45W adapter with that computer; it would not provide enough power for that MacBook."
Click to expand...

From experience, lower wattage adapters work. Power is going in up to the maximum wattage of the adapter. However, they may not provide enough power to charge the laptop, or it may charge more slowly.
 
Freyqq said:
From experience, lower wattage adapters work. Power is going in up to the maximum wattage of the adapter. However, they may not provide enough power to charge the laptop, or it may charge more slowly.
Click to expand...

Yeah, agreed. I've used my girlfriend's MagSafe 2 Air adaptor on my rMBP with no issue/warning. As you've said, probably didn't charge as quickly.

Didn't want to quote something that I couldn't back up with a link though!
 
SD-B said:
Hi I have 2 Macbook Pros from roughly the same time. Perhaps 10 months apart

They are almost the same. One is a 2.4 and one is a 2.56. One has the adaptor that snaps in as if from the side, whereas the other adaptor just snaps straight in.

I assume you will know what i mean by that horrible description, LOL but w hat i am wondering is if the two can be used on each machine back and forth.
Must one only work on one and the other, only on that one, etc since they are basically the same macbook pros?
Click to expand...

When are these MacBook Pros from? If both are from 2011 or older, then there should be no reason they wont work. Just be careful with wattage if one is a 13" and one is a 15". Using the cable from the 15" might be too much for the 13".

Now if one of your MacBooks is a retina from 2012 or 2013, then you can't use the MagSafes interchangeably because the retina MagSafe 2 is smaller.

Easier way to tell if you're not sure is of the straight-in cable (normally called t-shaped) is white plastic or aluminum. If it's plastic, it's the same as the other one (L-shaped). Aluminum is the MagSafe 2.
 
jg321 said:
As myself and others on this thread have said, the wattage doesn't seem matter either way in practice, although officially you shouldn't use a smaller one than originally provided.
Click to expand...

It matters plenty if you're going to be doing anything other than the most basis tasks.
 
jg321 said:
Explain please?
Click to expand...

The 85W adapter can barely keep up when doing things more intensive than word processing or web surfing. If I fire up a game or crunch video, sometimes the system will draw upon the battery to make up the power deficit.

It might not matter as much for older systems, but once Apple got to the Core i-Series CPUs, they should have boosted the 15-inch models' adapters to 120W. Razer, a company with far fewer resources than Apple, was able to create a streamlined 120W AC adapter for its Blade notebook. Surely Apple could have done the same.
 
saturnotaku said:
The 85W adapter can barely keep up when doing things more intensive than word processing or web surfing. If I fire up a game or crunch video, sometimes the system will draw upon the battery to make up the power deficit.
Click to expand...

Are you saying that even with the 85W adaptor plugged in, your battery drains when you fire up a game or crunch video? If so, how are you measuring this?
 
saturnotaku said:
You have that reversed.
Click to expand...

Using the lower watt cable with a 15" just means it will charge slower. I don't believe it's recommended to use the higher watt cable with a 13" to prevent burning it out. Like how you're not supposed to use the 10w charger for an iPad to charge an iPhone. I'm talking safety here, not getting more power for gaming.
 
jg321 said:
Are you saying that even with the 85W adaptor plugged in, your battery drains when you fire up a game or crunch video? If so, how are you measuring this?
Click to expand...

Yes, this can happen. You can see the battery drain, even with the power adapter plugged in, if the power draw exceeds what the power adapter can deliver.

This happens quite easily with the 45W and 60W adapters, but can also happen with the 85W adapter with heavily tasking applications.

KUguardgrl13 said:
Using the lower watt cable with a 15" just means it will charge slower. I don't believe it's recommended to use the higher watt cable with a 13" to prevent burning it out. Like how you're not supposed to use the 10w charger for an iPad to charge an iPhone. I'm talking safety here, not getting more power for gaming.
Click to expand...

You can safely use the iPad charger for an iPhone, and you can safely use a 85W charger for a laptop that only requires 60W. The devices only draw as much current as they safely can, the chargers can't force them to draw more.
 
thank you, my question was answered here but do continue on as others seem not to be sure either


thanks again :)
 
Due to smart systems higher power isn't much of an issue (notice I said "much"). the real issue is using an under powered adaptor that isn't able to keep up with the system.
 
NukeIT said:
Due to smart systems higher power isn't much of an issue (notice I said "much"). the real issue is using an under powered adaptor that isn't able to keep up with the system.
Click to expand...

Higher power is a complete and total non-issue.

An MBA that only requires 45W, does not draw any more than 45W, even when connected to an 85W power adapter.
An iPhone, that only requires 1A of current, does not draw more than 1A, even when connected to an iPad charger capable of supplying 2A.
(Ok, that's a bit of a simplification, they can draw more power if they are designed to do so. Both the MBA and iPhone could detect that a more capable charger is connected, and draw more current to charge a bit faster, within safe limits.)

It's always the device drawing current, not the charger pushing it. The device only draws as much current it's designed to, even if the charger would be capable of providing more.

Chargers with different voltages would be a different story, as higher voltages can easily damage the devices.
(And that's a simplification too: the three MagSafe chargers actually are different voltage each: 14,5V, 16,5V and 18,5V. But the laptops detect this, and are designed to work with the different voltages.)

Bottom line: Using chargers with higher wattage is not an issue.
 
laurihoefs said:
Bottom line: Using chargers with higher wattage is not an issue.
Click to expand...

Your correct there "shouldn't" be an issue, as I stated with smart systems. And I doubt you will ever experience an issue... However there is always a possibility.

I prefer to use the proper equipment when it is available.
 
NukeIT said:
Your correct there "shouldn't" be an issue, as I stated with smart systems. And I doubt you will ever experience an issue... However there is always a possibility.

I prefer to use the proper equipment when it is available.
Click to expand...

According to Apple, an 85W charger is suitable for a 45W or 60W MacBook: http://support.apple.com/kb/HT2346?viewlocale=en_US&locale=en_US

There is no issue, and the use of higher rated power adapters is officially supported and documented. I don't know why you claim there is some hidden danger, when there is not. Such a claim goes against Apple documentation, common user experience, and even basic knowledge of electronics.
 
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