What To Consider When Buying MacBook Pro Retina Power Adapters

The new MacBook Pro Retina is now shipping with the soon-to-be ubiquitous USB Type-C ports.   There are 4 of them on my new 15″ MacBook Pro.    The cool thing about these new ports is they are bi-directional and symmetrical. That means the cable is identical on both ends and there is no upside-down.   That is a HUGE step up from all previous iterations of cables and connectors.

In addition the new USB Type-C cables and ports can support video, audio, data, and power.   That means the ports can be used to connect headphones, monitors, and power to your devices.   For smaller devices like phones that means one port can be used to power your device while at home and the same port is your headphone jack when out roaming around the city.

However there are some key things to be aware of especially when you are talking about the USB Type-C ports and charging devices, especially when looking for a new MacBook power adapter.   As many people are learning, not all charging devices and cables are created equal.   As happens with any new tech peripheral, China has rushed into the USB Type-C market with dozens of low-quality accessories that are not up to the job.   Best case, your device doesn’t charge.  Worst case, your device is fried and you start a fire.

What you need to know — power supplies

Not all USB Type-C ports and devices are created equal.  Especially when it comes to power delivery.    Many devices that use the USB Type-C port for charging use a special system known as the “Power Delivery” specification or USB Type-C PD.    A USB-C PD cable and outlet use both the data part of the cable and the power delivery part of the cable to not only send power to your device but send data back-and-forth about how much power to send.

USB-C PD devices are “intelligent” power devices.   When you connect a USB-C PD cable to your MacBook Pro the MacBook starts talking to the power brick and tells it “hey, I need 20.2 volts at up to 4.3 amps”.    A power delivery compatible power supply will read that data and send exactly what the laptop needs.    Yes, that’s right, your power brick now is “intelligent” and is sending not only power but data back-and-forth to the device.

That is important to know when trying to charge your MacBook.   Plug it into a non-PD charging brick and you are rolling the dice.   Lucky for you nearly every Type-C power supply on the market today (November 2017) is significantly under-powered.    If you are using a 15″ MacBook Pro Retina you need to send it 87 Watts of power (20.2v x 4.3a = 86.6w).     Anything less and your MacBook will charge slowly, sometimes slower than the power being consumed if you are using it at the time.

What you need to know — cables

Now that you have a properly-sized power brick, which likely means the Apple 87W USB-C MacBook Power Adapter as I only found one other power supply that is rated at last 86.6W on Amazon and it does not specify that is is PD compatible (likely not as the connection is only 4 wires which is not enough for properly data + power delivery), you can move on to worrying about cables.

Yes, the cable matters.    How does a toaster work?  It sends a lot of current down a wire with a lot of resistance which makes it heat up.   While a toaster uses different materials to make it resist the transfer of energy and heat-up, another trick to do this is to force too much electricity down a wire that is too small.   Guess what?  The wires in a USB cable are extremely small.   Millimeters matter.     Buy a low-cost USB Type-C cable that is not designed to carry 87W of power and it will heat up and possibly catch fire.   Chances of that are slim, but it will heat up to the point of degrading the cable and eventually breaking it down.

The other thing to know is that a fully-compliant USB Type-C 3.0 cable has 15 wires. This ensures it is fully reversible and can carry data and power at the same time.    Not all cables are created equal.   USB 2 (the older ones with a “flat” end) to USB-C / USB-3 cables often only have 5 wires.  What wires are often missing?  The ones that carry a charge.

When buying a cable make sure it is USB Type-C 3.0 compatible and preferably USB Type-C Power Delivery / USB Type-C PD compatible AND rated for the proper wattage.    Apple has specific cables that can carry up to 87W for the MacBook 15″ Pro Retina.    While you can use a cable rated for higher wattage on a lower-demand device, like a smaller MacBook that needs only 61W it is not a good choice to go the other way around.

What to look for – cheap knock offs

In looking to avoid the $79 fee to get a second Apple 87W USB-C MacBook Power Adapter I scoured the Internet for hours.   Amazon had a TON of power chargers listed as 87W Type C Apple Compatible.   They are all incorrectly advertised.   Nearly every one of them is a the lower-end 61W charger that has been re-screen-printed to show 87W.  It will charge but not nearly fast enough to keep up with a 15″ MacBook Pro Retina.

You will also find a lot of lower-end USB Type-C cables.  You want to make sure you geta cable from a reputable vendor that is fully USB Type-C 3.0 compatible and is rated for at least 87W.

You also want to make sure the power supply is PD compatible.    You’ll find this is an issue with many USB Type-C devices.

To date I have found the ONLY 87W USB-C PD power supply available is the Apple charger which is $79 without a USB-C cable.  That will set you back an additional $20 from Apple, though there are some available on Amazon for less.

The good news is that Apple 87W USB-C PD power brick will power virtually any device on the market today that uses USB-C for charging.

In the meantime most other vendors of power supplies, power bricks, wall outlets, and other USB-C power sources are relegated to lower power phones and tablets, though even on those devices you want to be sure you have enough amps to charge the devices quickly.   Often you can save a few-dollars on a device but are trading a 5A output for a 2A output which will take eons to charge your tablet.


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