One of the things the coronavirus-induced lockdown has made me appreciate is the benefits of a large monitor on your home office. That, and a laptop that actually has an HDMI port for that. If you’re a Mac user like me, stuck at home trying to work on an external monitor with your laptop, chances are you don’t want your laptop screen shining at the periphery of your vision. It’s very entertaining. So you probably want to close your laptop’s lid and use the external display as your main monitor, right. Plus, you want to do this without connecting a power adapter all the time. So here’s how to use a MacBook in clamshell mode without an AC adapter.

Use MacBook in Clamshell mode without a power adapter

Why don’t MacBooks support this by default?

Why do we need an entire article on how to do this? Well, turns out Apple won’t let you do that unless you have a power adapter plugged into your MacBook. Take a look at the company official help document about that. Now when I started out with this whole setup, I took Apple’s word for it and continued to use my MacBook with the charger attached at all times, knowing full well that it would destroy my battery health . That’s exactly what I did and my battery won’t charge anymore. Now I’m stuck using my laptop as a glorified desktop computer and with an incredibly throttled CPU to boot.

Lucky for you, this got me looking for ways to use a MacBook in clamshell mode without keeping the charger always connected, and I found the solution.

MacBooks manage power in a way that isn’t very obvious. You know, unless you do what I did and get lost in forum threads about the “hibernatemode” command and the different power states of a MacBook. I’ll give you the long and the short.

Basically, when you close the lid of your MacBook, it goes to sleep. This means it stops powering external displays, readers, even the Ethernet port (if it has one). Now, a user normally expects the laptop to be smart enough to know that an external display is connected to it. This obviously means that I want to use it as my main screen. But, our Apple overlord knows better than we do what we want and does not allow this particular setup to work.

There are a bunch of terminal commands you can use to disable sleep, and we’ll discuss them in a later section, but chances are you don’t want to mess with terminal commands and a simple one-stop solution. click is really all you’re looking for.

Save Mac Battery by Using it in Clamshell Mode Without an AC Adapter

Now that we know that the problem is that the MacBook goes to sleep by closing the lid even though we have an external display connected, the solution is simple. We must stop this sleep from happening. But you can’t just use a simple Caffeine-like app to solve this problem. That’s because your MacBook’s Hall Effect sensor detects when the lid is closed and simply puts it to sleep regardless of everything else.

Using a third-party app

You must have heard of the “Amphetamine” app, which is an extremely popular Mac app that controls sleep states for the Mac based on triggers and the like. Although the app originally did not have the ability to fix our problem, it has since been updated and can actually help us out of this mess.

  • To get started, go to the Mac App Store and download Amphetamine (To free).
  • Launch the app and you will be greeted with a screen like this. Click on ‘Following and follow the instructions.
  • Now click on the Amphetamine icon in the menu bar.
  • Head to “Quick Preferences” and uncheck the box next to “Allow system to sleep when screen is closed”.
  • You will see a warning window suggesting you to install Amphetamine Enhancer. This is optional, but recommended. You can just click the button that says “Get Amphetamine Enhancer” to go to the website and download the helper app. Alternatively, just Click here to download it.
  • Install the wizard and launch it. To select “Failsafe Closed Display Mode” from the sidebar and click ‘Install’.
  • Click again on the Amphetamine icon in the menu bar. Make sure you have unchecked the box next to ‘Allow system to sleep when screen is closed‘.

That’s it, you can now use your MacBook in clamshell mode without having to connect your power adapter to it.

Using Terminal Commands

If you don’t want to use a third-party app to achieve this, or if you just want to play around with terminal commands and figure things out on your own, some commands can achieve similar results.

To note: I haven’t tested these commands because Apple recommends against changing hibernation using the pmset command, and these commands do just that. However, these commands will disable your laptop’s sleep on the lid close trigger, so they should also fix the problem of not being able to use your laptop in clamshell mode without the power adapter. That said, use them at your own risk.

With that warning out of the way, here’s what you need to do.

  • First, launch the terminal and run the following command to see your default ‘hibernatemode’ setting. Be sure to note it.

pmset -g | grep hibernate mode

  • Now run the following commands in the terminal.

sudo pmset -a sleep 0 sudo pmset -a hibernatemode 0 sudo pmset -a disablesleep 1

These commands will disable sleep on your MacBook and should be able to use your Mac in clamshell mode without a power adapter connected.

You can always revert changes by running the following commands in terminal

sudo pmset -a sleep 1 sudo pmset -a hibernatemode sudo pmset -a disablesleep 0

Use MacBook in Clamshell Mode without AC Adapter and Save Your Battery Health

I may have knowingly rendered my MacBook Pro’s battery completely unusable to the point that it won’t even charge, but you don’t have to follow in my footsteps. Now that you know how to use an external display with your MacBook without having to keep an adapter connected all the time, go ahead and set up your work from your home office with your brand new monitor and enjoy working on a bigger screen with more real estate. Oh, and whatever you do, don’t take Apple’s word for it on this stuff. In the meantime, I’ll try to figure out if I should buy the MacBook Air M1 or the MacBook Pro M1.