MacBook Pro – Can 3rd Party Chargers Cause Damage

Most switching power supplies are most efficient when operating at 50% capacity. And they're definitely pretty inefficient at less than 20% capacity.

Since the MacBook draws less power than a MacBook Pro, I would suspect that an 85w power supply would work just fine, but the larger power supply for the MBP probably would draw more power from the wall socket than is necessary when connected to a MB because it is operating in a suboptimal capacity range.

Here's an example: Take for example the 45w power supply for the MacBook Air. Sure you could hook up the 85w power supply, but since the MBA might only draw 20 watts, the power supply is operating at less than 25% capacity. At this capacity, the power supply may only be 60% efficient (an educated guess), that means the power supply has to draw 33 watts of AC power just to supply the laptop with 20 watts of DC power.

Long story, short: It's a power conversion efficiency thing. I'd say buy the one that is designed for your laptop so that you save energy.

The Apple cables appear to be designed to safely melt without starting a fire in cases where the internal insulation breaks down in case of crushing, slicing, piercing (kittens are even worse than cats in this regard) or simply worn out due to repetitive bending in the same spot.

I've seen people decide to use cords when lightly damaged - sealing the cable with electrical tape. Since the voltage is low on the MagSafe side of the cord, this is more a heat/fire risk than a shock risk. The MagSafe board on the Mac usually protects your hardware from any sort of short - and it also is replaceable if it's fusing blows.

I have on rare occasion seen some nice third party adapters that work with MagSafe connections - but none yet on MagSafe 2. I have seen far, far more dangerous adapters than safe ones.

The worst part of counterfeit adapters is that they typically carry the same "safety" markings as a quality electronics adapter. Also, some have high quality plastics and similar weight so you may have to be very observant to tell a good knockoff from a genuine part. Unless you are using the adapter in an environment where a small fire could reasonably be contained without undue risk to finances or life, you might avoid using a third party adapter if you are not skilled at evaluating electronics for build quality.

• http://www.righto.com/2015/11/macbook-charger-teardown-surprising.html?m=1

The article above explains how the Apple charger is engineered with a processor in the MagSafe connector and a main processor that's equivalent to the original Macintosh - you're getting a computer inside every Apple charger as well as dense and highly safe design shown on the left and a knockoff design on the right.

I've been well served by buying Apple adapters in terms of reliability and safety, despite the higher cost. I know many that have had good luck with quality third party adapters, but wanted to explain the why some third party adapters are dangerous to use and not even close to equivalent to Apple's product.