Mac Shutting Down Randomly? Here’s What You Can Do
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You’re working on an important assignment in Microsoft Word, or you’re surfing the web and your Mac shuts down randomly. Most of the time, this never happens again, or at least not too often.

But if you’re dealing with a computer that is habitually shutting down, you may have a bigger problem on your hands. Today we’ll discuss ways to resolve this issue, tools to help fix your Mac The 8 Best Free Mac Tools to Detect and Fix Common macOS Problems The 8 Best Free Mac Tools to Detect and Fix Common macOS Problems Every Mac user should keep these 8 tools around to fix any problems that may arise, like malware, hardware issues, and more. Read More , and (hopefully) make sure it never happens again.

It Happened, Now What?

When your Mac experiences a random shut down, the best thing to do is reboot it and immediately restart it again. This two-step process is necessary because some programs don’t always shut down correctly the first time around. To begin the second reboot, select Restart from the Apple menu.

Unfortunately, just rebooting your Mac might not solve the problem. If this is the case, Apple recommends resetting the computer’s System Management Controller How To Reset Your Mac's SMC & PRAM – And Why How To Reset Your Mac's SMC & PRAM – And Why Sometimes your Mac will act strange for no apparent reason, and if a restart doesn't work, sometimes you'll need to reset the SMC and PRAM. Read More , or SMC, which is a subsystem of Intel processor-based Macintosh computers. It is similar in function to the older System Manager Unit (SMU) or Power Management Unit (PMU) of non-Intel Macintosh computers. The SMC controls your computer’s thermal and power management, battery charging, video mode switching, sleep and wake, hibernation, and LED indicators.


Before resetting the SMC, Apple recommends doing the following steps, in the order they are listed:

  1. Press Command-Option-Escape to force quit any application that is not responding.
  2. Put your Mac to sleep by choosing Sleep from the Apple menu. Wake the computer after it has gone to sleep.
  3. Restart your Mac by choosing Restart from the Apple menu.
  4. Shut down your Mac by choosing Shut Down from the Apple menu.
  5. If your Mac isn’t responding, force the Mac to shut down by pressing and holding the power button for 10 seconds. You’ll lose any unsaved work in any open applications.

Time to Reset

Once these steps have been exhausted, it’s time to reset your SMC. The steps involved vary, depending on whether your system has a removable battery. Mac notebook computers that have a nonremovable battery include MacBook Pro (Early 2009) and later, all models of MacBook Air, MacBook (Late 2009), and MacBook (Retina, 12-inch, Early 2015).

If the battery is non-removable:

  1. Shut down the Mac.
  2. Plug in the MagSafe or USB-C power adapter to a power source and to your Mac.
  3. Using the built-in keyboard, press Shift-Control-Option on the left side of the keyboard, then press the power button at the same time.
  4. Release all keys, then press the power button again to turn on your Mac

If the battery is removable, do the following:

  1. Shut down the Mac.
  2. Disconnect the MagSafe power adapter from the Mac.
  3. Remove the battery.
  4. Press and hold the power button for 5 seconds.
  5. Reconnect the battery and MagSafe power adapter.
  6. Press the power button to turn on the Mac.

Finally, on iMac, Mac mini, Mac Pro, and Xserve:

  1. Shut down the Mac.
  2. Unplug the power cord.
  3. Wait 15 seconds.
  4. Plug the power cord back in.
  5. Wait five seconds, then press the power button to turn on the Mac.

Maintaining a Healthy Mac

Macs last for a long time, but they can develop problems with age. Thankfully, there are some steps you can take to make sure your Mac continues to run smoothly, or at least know before trouble hits.

Monitor Your Battery

Rechargeable batteries don’t last forever. Use of your Macbook notebook battery accrues in the form of charge cycles. Each battery is only good for a limited number of charge cycles. At that point, the battery is consumed and must be replaced.

You can see your Mac’s current cycle count by holding the Option key and clicking the Apple Menu. Choose the option to open System Information. Under the Hardware section of the System Information window, select Power. Under Battery Information, you’ll see the current cycle count.


The maximum cycle count varies by notebook model. Some, such as the early MacBooks, only offered 300 cycle counts. Newer models usually last for up to 1,000 cycle counts. A charge cycle means using all of the battery’s power, not necessarily a single charge. It might take several days to complete a cycle.

When your computer has reached its maximum cycle count, it should be replaced.

Third-Party Tools Do Even More

You can learn much more about your Mac’s battery by using a third-party application such as coconutBattery or Battery Health. These tools go beyond cycle counts CoconutBattery: Your Mac Battery's Health Simplified CoconutBattery: Your Mac Battery's Health Simplified Read More and explain things in less technical terms. With these tools, for example, you can track battery temperature, status, design capacity, and more.


Checking your battery’s temperature is also very important. A battery that frequently overheats suggests bigger issues. Tools like Battery Health show how much longer your battery will last on its current charge using real-life metrics. For example, the time remaining to surf the Internet, listen to music, or watch a movie. You can also use these applications to track the battery status over time. This information could prove very useful in the long-term.

Reading the Logs

The less you need to charge your battery, the longer the battery should last and the healthier your computer can remain. Conversely, applications that are consistent battery hogs can cause long-term damage to your investment.


The easiest way to see which applications are using up the most battery life on your MacBook is to select the battery icon in the menu bar on the upper-right corner of the screen. Here you can see “Apps Using Significant Energy.”

You should also use your Mac’s Activity Monitor Activity Monitor: The Mac Equivalent of Ctrl+Alt+Delete Activity Monitor: The Mac Equivalent of Ctrl+Alt+Delete If you want to be a fairly proficient Mac user, it is necessary to know what Activity Monitor is, and how to read and use it. As usual, that's where we come in. Read More , which shows you the applications and services that are using up the most CPU power. Go to Applications > Utilities > Activity Monitor. Pay careful attention to the items located under the CPU and Energy tabs. Large numbers could be troublesome.

Save Your Energy

You should also check your computer’s Energy Saver settings, which are located in the System Preferences menu. For most users, the default settings are appropriate. Click “Restore defaults” for those settings.

Calibrating Your MacBook Battery

Batteries on older Macs should be calibrated once a month Calibrate & Maintain Your MacBook Battery For Best Performance Calibrate & Maintain Your MacBook Battery For Best Performance If you correctly calibrate and maintain your MacBook battery, it's possible to improve performance and put off replacing it for as long as possible. Read More . According to Apple, MacBooks, MacBook Pros, and MacBook Airs released after mid-2009 are pre-calibrated and don’t require calibration.

As we previously noted: “A properly-calibrated and battery will help you keep tabs on your power source and prevent the annoyance of having your computer not give you a warning before it goes to sleep or telling you that it has a few minutes left when it could easily go for another few hours. After a successful calibration, your MacBook’s battery meter will be a lot more accurate.”

Contact Apple

If your Mac continues to shut down randomly Mac Won't Boot? A Step-by-Step Guide to Waking It Up Mac Won't Boot? A Step-by-Step Guide to Waking It Up If your Mac won't turn on, don't despair. Our guide to troubleshooting MacBook and iMac boot problems will get you running again. Read More even after using the troubleshooting tools mentioned above, it’s time to visit an Apple retail store, or an approved service center. You can also contact Apple through the company’s support page.

If you’re feeling brave (and your warranty has run out) then you might want to head over to iFixit, find guides for your machine and try and fix it yourself.

Image Credit: Angry businesswoman by Dean Drobot via Shutterstock, Micolas via

Explore more about: Battery Life, MacBook, MacBook Air, Troubleshooting.

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  1. John
    March 16, 2018 at 2:51 pm

    And none of those solutions address the AppleThunderboltNHI bug.

    Rename /System/Library/Extensions/AppleThunderboltNHI.kext to /System/Library/Extensions/AppleThunderboltNHI.kext.BAK and the problem will go away.

    Restart in Recovery mode (hold ?+r at Startup). Enter Terminal and type:

    csrutil disable

    to turn off System Integrity Protection (you cannot rename the file otherwise).


    Enter Terminal and type:

    sudo mv /System/Library/Extensions/AppleThunderboltNHI.kext /System/Library/Extensions/AppleThunderboltNHI.kext.BAK

    Crashing is now solved.

    Now turn System Integrity Protection back on by restarting in Recovery mode (hold ?+r at Startup). Enter Terminal and type:

    csrutil enable

    Restart and enjoy your Mac as normal.

  2. Chris
    February 5, 2018 at 10:31 pm

    Please my Amperage (mA): is -480 can it be the cause of unpredictable shut down?

  3. Natalie Donaldson
    August 14, 2017 at 1:35 pm

    excellent article. super helpful. thank you.

  4. Hush
    May 3, 2016 at 9:23 am

    ....never happened to me :S
    very often instead it won't shut down, what about that?