60W Magsafe showing as 85W

[AeroZ]

Hi,

I just replaced the cable of my Magsafe 60W adapter with this http://www.ebay.co.uk/itm/400830376957?_trksid=p2059210.m2749.l2649&ssPageName=STRK:MEBIDX:IT.

Now going into About this Mac->System Report->Power shows that the AC charger is 85W not 60W.

How's that possible?

 

[catzilla]

One knockoff cable for all magsafe wattages. There is a chip in the plug that tells the 'book the specs of the charger.
http://www.righto.com/2013/06/teardown-and-exploration-of-magsafe.html

 

[AeroZ]

One knockoff cable for all magsafe wattages. There is a chip in the plug that tells the 'book the specs of the charger.
http://www.righto.com/2013/06/teardown-and-exploration-of-magsafe.html

Yes, I read that article too.
Tho the question is, is it OK if the system shows 60W charger as 85W or it might cause some serious problems?

 

[damidget]

Yes, I read that article too.
Tho the question is, is it OK if the system shows 60W charger as 85W or it might cause some serious problems?

It should be fine seeing as its rated from 45W-85W.
Just be careful with it

 

[Gjwilly]

Yes, I read that article too.
Tho the question is, is it OK if the system shows 60W charger as 85W or it might cause some serious problems?

I'm in the same boat but sailing the other direction.
My 85w charger is now showing up as 60w.
We should have swapped cables.

I'm thinking that I'm a little better off though because if the chip in the Magsafe tells the MacBook what charger you're using then your charger is always going to be overtaxed.
The MacBook is going to be trying to draw 85w out of a charger designed for only 60w.
That's going to lead to excessive heat at the very least.

 

[joe-h2o]

I'm in the same boat but sailing the other direction.
My 85w charger is now showing up as 60w.
We should have swapped cables.

I'm thinking that I'm a little better off though because if the chip in the Magsafe tells the MacBook what charger you're using then your charger is always going to be overtaxed.
The MacBook is going to be trying to draw 85w out of a charger designed for only 60w.
That's going to lead to excessive heat at the very least.

No it won't. It will draw 60W as before. The MBP will draw the power it is designed to from the charger (if able), so a 13" MBP will draw around 60W at full load.

From Apple's own pages: http://support.apple.com/en-us/HT2346

Using an adapter of higher wattage than the adapter that came with the computer will not cause the computer to charge more quickly or otherwise operate any differently than using the adapter that came with the computer.

 

[priitv8]

No it won't. It will draw 60W as before.

But it won't work the other way around - i.e. 15" MacBook Pro won't attempt to draw 85W out of a 60W (or 45W) charger.
Otherwise the charger brick would catch fire.

 

[steve62388]

But it won't work the other way around - i.e. 15" MacBook Pro won't attempt to draw 85W out of a 60W (or 45W) charger.
Otherwise the charger brick would catch fire.

You should try to source this information direct from Apple just to be sure, it's probably on their website somewhere. Because a normal device would draw the additional power and this could result in a potentially dangerous situation.

 

[priitv8]

I have run my 15" MBP off of a 65W charger. No fire. Just charges slower.

 

[TheIguana]

I have run my 15" MBP off of a 65W charger. No fire. Just charges slower.

Keep in mind that your computer will make up the additional power required from the battery if you exceed the amount of power that the adapter can supply.

But yes that is right... except in this case they are talking about repairing a broken adapter by grafting a new MagSafe cable on to it.

Specifically, in this case they are talking about grafting a MagSafe cable from an 85W charger onto a 65W charger (by accident). Since the cable contains the circuitry telling the Mac what wattage adapter is connected it could cause problems. For instance if this adapter were plugged into a 15" MBP that needs 85 Watts and tries to pull that from the charger it could overload it - unless Apple has built in further redundancy into these chargers.

 

[AeroZ]

So what's the final verdict?