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Did you know that you can use a higher power charger to recharge your MacBook Air / Pro? [atualizado]

My wife recently ?lost? her MacBook Air charger. ?Lost? because we know it?s somewhere here at home, but it?s been more than a month that we?re looking for and nothing

The simplest solution would be to invest in a new charger, but this is also the most painful, after all, one of these costs R $ 349.

MagSafe 2 charger

Since the charger decided to play ?hide and seek? and I?m not at least willing to buy a new one for now, I decided to investigate whether her 13-inch MacBook Air can use my charger (from a MacBook Pro with Retina display) 15 inches).

Before the answer, let's recap things. Currently Apple works with three different chargers for its notebooks, all of them with the new MagSafe 2 connector (thinner than previous models).

  • 45W: for 11 and 13 inch MacBooks Air;
  • 60W: for MacBooks Pro with 13-inch Retina display;
  • 85W: for MacBook Pro with 15-inch Retina display.

As you can imagine, my wife's MacBook Air charger is 45W, while mine is 85W. Even before looking for information I was already afraid, after all, the difference in power is huge. But what was my surprise to see that, yes, it is possible to charge a MacBook Air with an 85W charger!

Here's what Apple says about it:

Apple laptop chargers with an Intel processor are available in 45W, 60W and 85W. Although you should always use a charger with the power (in watts) suitable for your Apple laptop, it is okay to use a charger with greater power.

For example, 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. However, you could not use a 45W charger with this MacBook, as it would not provide enough power for the computer to function.

By doing this (using a charger with a higher power than the original charger provided), however, the computer will not be charged any faster. Apple does not explain, but most likely notebooks and / or chargers have some way to manage power. That is, as much as the MacBook Air is connected to an 85W charger, it should only use 45W.

Thinking about it, notebooks follow the same logic as iGadgets. IPhones, for example, come with a 5W charger, while iPads with a 9.7 inch screen (iPad Air and fourth generation) come with a 10W. An iPhone can be charged normally with a 10W charger; an iPad Air * no * can be charged with a 5W as there is not enough power to recharge.

So here?s the tip: if you?re out and about and your Mac?s battery is running low, you can borrow a charger without a problem as long as it?s equal to or higher than your notebook?s charger.

For more information on the different charger models (MagSafe L, MagSafe T and MagSafe 2), this Apple support article is worth visiting.

Update · 06/30/2014 s 20:32

Forgive the ignorance of this humble editor.

After the post was published, some readers explained how it works. We took the statement from Alexandre Henrique Pott to exemplify the process:

In fact, it is not necessary (something to) manage the power. That number (85W) would be the maximum power of the charger.

Power is a product of voltage (volts) vs. current (ampres). The tension needs to be the same. The current, which is the flow of electricity that the device demands from the source, needs only to be supported by the source (that is, it must have an indication in pressure equal to or greater than what the device needs). Therefore, if there is a higher consumption (more current), the power will therefore be greater and vice versa.

When you leave the charger plugged into the outlet with nothing attached to it, the effective power tends to zero in practice the internal circuits of the source still consume some electricity. If you did the opposite (plugging in a MacBook that requires more current from a lower power source) something would not go well. It could possibly take longer to charge (or even charge properly), which could cause the power supply to overheat.

Properly explained. And as the reader Caio Ferrari he said, ?this information should be given in any basic electricity course in high school. What a pity that this is not the reality. ?