I'm a technician and noticed that, if the battery is disconnected in a Macbook/MacBook Pro: the Mac boots itself when you connect the power adapter. It sometimes even happens when the battery is connected (after I disconnected and connected it). What rules this?

2 Answers 2


A Mac laptop will boot itself when power is connected if (a) the firmware power on time has passed since the machine was last running (i.e. if the machine was set to power on at 6 AM every morning and it has been 6 AM since it was last powered on) OR if the machine was on (not shutdown properly) before power was removed.

The concept is that if power is lost, a Mac should return to the state it was in.

If you want to ensure that the machine does NOT power itself on,

  1. In System Preferences -> Energy Saver ->Schedule..., remove any rule that states the machine should power on at a given time.
  2. Shutdown the machine correctly by selecting "Shut down..." from the Apple menu and waiting until it is completely shut down.
  • I noticed the happened consistently when I was running Ubuntu. Had to plug in before shutting down, every time. Would this indicate Ubuntu was not actually shutting down properly? If so what might be the root cause? Commented Apr 4, 2019 at 11:19
  • Hi there. You said the Mac will start itself "if the machine was on (not shutdown properly) before power was removed.". I've done some testing on a Macbook pro 13" 2015: I shut it down properly, then opened it and disconnected the battery, then connected the magsafe adapter: it started itself instantly. Commented Apr 13, 2019 at 8:10

Bill, that’s not really pertinent to what Antonio was asking. Yes, there are rules defining power schedules but his specific query can also be applied to the iPhone, iPad and Apple Watch. Every Apple device powers itself on when it goes from a state of not connected to power to connected to power

It’s possible to power an Apple device off when it’s plugged in, but if you unplug it and plug it back in, it will immediately power on.

This is clearly something Apple carries with it and seems to be their MO, that a device that’s powered should be able to be worked with immediately. It’s a QoL situation

I think we can think of this in the same way that closing the lid on a MacBook will always sleep it (without being able to modify this behaviour outside of an Apple like Amphetamine) or closing a Smart Cover on an iPad will immediately put it to sleep.

My educated guess is that this is hardwired into the system, if power detected and device = off, turn device on. Again going back to QoL. Apple wants to ensure people have immediate access to their devices and it’s clear they are bypassing checks for batteries. I would be very intrigued to know if this behaviour is reproducible on a device like an iPad/iPhone. I don’t think it would for the watch due to the design, but I’d be interested in knowing the answer for say the iPad.

  • not sure you are correct here, I have a macbook with no battery and I can disconnect / re-connect the power and it does not start... I have to cycle the power button...
    – Solar Mike
    Commented Apr 4, 2019 at 7:01
  • Interesting. I wonder if it relates to the model. OP states to be a technician and has a fair bit of empirical evidence that seems to hack up their statement, but also has not defined the specific models he’s tested in. Which model do you have? Hopefully OP will come back with more details, as otherwise we could simply be comparing apples and oranges here.
    – Nick
    Commented Apr 4, 2019 at 7:12
  • I think the other answer is most likely - ie it returns to the state it was in...
    – Solar Mike
    Commented Apr 4, 2019 at 7:14
  • @SolarMike: Not disputing your assertion, and I've not studied Apple's wiring, BUT the fact that it behaves differently with the battery removed doesn't mean that Apple hasn't "designed in" this behavior.
    – Seamus
    Commented Apr 4, 2019 at 14:23
  • @Seamus so you seem to agree then with the other answer...
    – Solar Mike
    Commented Apr 4, 2019 at 15:00

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