Can I Use an Older MacBook Pro Power Adapter Extension on a Newer One?

Yes. You can use your older MacBook Pro adapter extension to charge a new one, but only if you use an extension cable. With the launch of the latest 2018 MacBook Pro, users have discovered that their older third-party power adapters and extension cables are not compatible with the new machines. This is because Apple has introduced a new type of connector on its latest MacBook Pros called “USB-C Power Delivery,” which provides up to 60W of power.

Users who own older versions of the 15-inch MacBook Pro can only use a maximum of 30W when connecting their computer to an external power source. Unfortunately, it’s impossible to use an older power adapter with a newer Mac without an intermediary device (such as an extension cable) or buy a unique power adapter specifically designed for the latest models.

Why Can’t Older MacBook Pro Power Adapter Extension be Used with Newer Macs?

The latest MacBook Pros are the first generation of machines with a USB-C port rather than a MagSafe connector. They ship with two USB-C ports instead of one, which has led to confusion about which one is used for charging.

Apple changed how the USB-C ports charge the Mac by providing 60W through the port rather than 29W, as it was with the previous design. The new design also includes a different type of connector used to transfer data and power to the MacBook Pro.

This change in charging method means that older MacBook models won’t recognize a new power adapter as valid and will, therefore, not allow it to charge the computer.

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How to Identify a Compatible Power Adapter

There are a few ways to identify if you have a compatible power adapter. You will need a voltage/current/power (V/I/P) meter to check the power rating. A multimeter will also work.

  • Plug your adapter into a wall socket, then check the reading on the meter to see if it’s above 31 volts. It will work with the latest MacBook Pro models if it is.
  • Another way to identify a compatible power adapter is to check the model number printed on the adapter’s casing. To do this, unplug your power adapter from the wall outlet, and flip it over to find the model number printed on the rear.

Note that model numbers are case-sensitive. They may be printed in a mix of upper- and lowercase letters or all uppercase letters.

How to Tell If You Have an Older or Newer Adapter

If you’re unsure if you have an older or newer model of adapter and cable, the fastest way to check is to plug both into the Mac. If the computer charges, the power adapter is compatible and will work with the MacBook Pro.

The first difference is that the older ones have a 30W rating and only one USB-A port. The newer ones have a 60W rating and two USB-A ports. If unsure, you can change the USB-A port designation on the older models. Here is how to change the USB-A port designation:

The left-side USB-A port is the primary out-of-the-box on the 15/15mac (2015 model) and the 13/13mac (2017 model). If you want the other port to be the primary:

  • Hold the Option key on your keyboard, click the volume icon in the top-right of the screen, then click “About This Mac” in the drop-down menu.
  • Select “System Information” from the drop-down menu, then search for “USB” in the list.
  • You’ll find a “Model” field for each port. Select the port you desire to change, click “Model” in the drop-down menu, then click “reset” to change the port designation.
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The Differences Between Old and New MacBook Pro Adapters

The most significant difference between the two is the power rating. The older adapters have a 30W power rating, while the newer adapters have a 60W rating. You will need an extension cord with the older adapters to charge the MacBook Pro.

Additionally, the older adapters have a single USB-A port, while the newer adapters have two.

The older models also have a different design for the connection slot where the plug is inserted into the adapter.

The last difference is that the new adapters come in either black or white while the older ones are black.

Understanding the One Type-C USB Port and Two Standard-A Ports

The USB-A ports charge your devices and transfer data via USB. The USB-C port is used for charging the computer and transferring data via USB. It would be suitable to plug the power adapter into the MacBook Pro’s USB-C port to charge the computer. The USB-A ports on the adapter will not charge the computer; they are used to charge your other devices.

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Understanding Which Extension Cord You’ll Buy

If you use an extension cord with your older adapter, the first thing you will want to check is the length of the cord. To do this, measure the distance between the wall outlet and the computer and then look for an extension cord of a similar size.

Next, you’ll want to check the type of connector at each end of the cable. Make sure that both connectors are USB-A.

The last thing you will want to check is the amps of the extension cord. A lower-amp extension cord will not provide enough power for the computer to charge. You will want to ensure the extension cord has a high enough amp rating (18AWG or 16AWG is best).

With the right extension cord, you will charge your new MacBook Pro using the older MacBook Pro’s power adapter extension.

How to Tell the Difference between USB-C Power Delivery and USB-C Connector

You must ensure the cable has a USB-C connector when shopping for an extension cord. The USB-C connector looks like a circle with a line through it. The computer uses this connector to draw power as well as transfer data.

How to Tell the Difference between USB-C Power Delivery and USB-C Connector

If you see a USB-C PD or PD (Power Delivery) on the extension cord, it is compatible with the latest MacBook Pro models. The older USB-C connectors are used with MacBook computers and do not produce enough power to charge the latest MacBook Pro models.

Frequently Asked Questions

What’s a USB-C PD (Power Delivery)?

USB-C Power Delivery is a standard that allows devices to transfer a large amount of power through the same cord used for data transfer. You no longer have to use a separate cable to charge your computer and devices.

With Power Delivery, the same cable can charge your computer, charge a phone, transfer data between devices, or even power an external hard drive.

Can I Use a New MacBook Pro Power Adapter on an Older One?

The short response to this question is no. The long answer is that it will not charge your computer because the voltage/current/power (V/I/P) ratings are different. Also, it will not transfer data. The data pins on the USB-C port are not connected to the computer. This is done intentionally because data pins are used for other things, such as computer charging.

Can I Use a Low USB Extension Cable?

Not always. Some cables may be used for charging only and not for data transfer. Although the connectors on a USB-C cable are standard, some still have 17-pin connectors, which means that they will work well with older devices.

Because older devices can use an additional connector to connect to power, it’s a good idea to check with your local computer dealer if you’re using a low USB extension cable.

When could I Use an Adapter?

Your computer owner has many options. Before making any decisions, consider these:

  • If your iPad or iPhone uses a low connection, connect it to the computer through the USB-C ports instead of charging it directly. This means your power adapter has more power available, so you can charge your device without having to plug in and unplug the adapter before connecting it to the computer.
  • If you’re connected directly to the computer with a wired or wireless connection, be sure that your computer has enough amps or juice left in its power supply (your old-style one). This leaves enough juice for charging either your device or another person’s device through a conventional USB port (like your PC port). A high power limit on an adapter may limit how many compatible devices can work at once, limiting any possible installation errors from getting into trouble.


The latest MacBook Pro models come with a USB-C port, which is used to charge the computer and transfer data between devices. It’s essential to note that the USB-C port is not used to transfer power. The power is transferred via a USB-C cable.

When shopping for an extension cord, it’s essential to have a USB-C connector on both ends. This will be indicated by the presence of a circle with a line through it on the connector. The USB-C port is used to charge your computer and transfer data. It is not used to transfer power.