Questions tagged [power-management]

Questions about with tracking and reducing power-drain for computers or devices.

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27
votes
4answers
58k views

Difference between autopoweroff and standby in pmset

I just got a new Retina MacBook Pro 15". After getting some downloads interrupted due to the computer going to sleep (even on AC power), I started looking at the man page for the pmset command. I ...
3
votes
2answers
3k views

How to detect if Mac if rebooting after a power failure using terminal?

As I asked in the title, how can I check if a Mac is rebooting after experiencing a power failure. It would be preferable to check this using terminal or some other script, as I would like to test ...
18
votes
6answers
23k views

kernel_task consumes 500% CPU on AC power, sometimes

Typically, my kernel_task process uses 1-4% CPU and 100-700MB of memory. However, sometimes when I have the power adapter plugged in, the CPU usage jumps to around 500% (8 cores) and stays there until ...
17
votes
2answers
8k views

Mountain Lion sleeps too aggressively

For me, Mountain Lion always seems to sleep whenever there is no user action, even when the computer is still doing something. In my case it always sleeps in the middle of running a batch operation in ...
7
votes
1answer
14k views

Disable Stand By Mode on Retina MacBook Pro?

I learned that the retina MacBook Pro has a Deep Sleep Mode that is initiated when left idle for a long time. This, however, causes my laptop to take about 3-5 seconds to wake up after it sleeps, such ...
3
votes
3answers
4k views

Prevent iMac from sleeping, for VPN login?

We have an iMac in the office, and I have been getting inconsistent access when trying to log in to it. The firewall isn't going down, since I can connect to the VPN. After discussing it with the ...
8
votes
1answer
24k views

How much power can be drawn from the lightning connector by a external device?

How much power can be drawn from the iPhone/iPad lightning connector by a external device? Update: The use case is a audio-related device for iPhone/iPads. It would require around ~100 mA at 3,3 ...
8
votes
6answers
12k views

Why does my laptop shut down overnight?

Whenever I leave my MacBook Pro (Retina, 13-inch, Early 2015) unattended (plugged in, or not) overnight (or for long periods of time) it shuts down by itself. When I open the lid it boots up to the ...
3
votes
1answer
4k views

When should I reset the SMC on a Mac?

I want to know when I should reset the SMC on a Mac. I have a very quirky G5 and was wondering if resetting the SMC would fix some of its problems.
3
votes
3answers
2k views

Is InsomniaX working on Mavericks?

It seems to me that InsomniaX, a utility to let a MacBook stay awake when the lid is closed, is not working on Mavericks. Can anyone confirm for me?
2
votes
2answers
570 views

“Battery Health” in macOS Catalina 10.15.5?

I have just installed the macOS Catalina 10.15.5 update on my 11" Mid 2013 MacBook Air. The update is working fine. The MacBook Air specifications on the Wikipedia page says that this model has a ...
2
votes
4answers
6k views

Limit processor speed like in Windows

In Windows (Linux too), you have the very useful "Power saver" mode that limits the maximum frequency at which your CPU runs. Is there something similar in OS X?
0
votes
1answer
2k views

Macbook Air shutting off on lid close

Every time I close the lid of my Macbook Air, it turns off and I have to manually start it later when I open the lid again. It also doesn't persist some of my settings such as volume level, desktop ...
35
votes
3answers
123k views

What is the “wake for wifi network access” setting in energy preferences?

Can anyone explain the "wake for wifi network access" setting in energy preferences for me? I do not understand it.
22
votes
2answers
20k views

Sleep timeout missing from the energy saver preferences

I have two Macbook Pros running on Yosemite. The first one is a 17 incher from 4 years ago. I'm able to set the time that it sleeps. The second one is a 15 incher retina made this year. In its energy ...
12
votes
5answers
16k views

Mountain Lion aggressively hibernates

Recently, my MacBook Pro (mid 2012, 15 inch, 10.8.2) has started going into what seems to be hibernate mode after several hours asleep, whether it's plugged in or on battery. When I unplug it, it ...
6
votes
3answers
16k views

How to keep monitor off when logging in remotely

I'm managing an 8-core mac server (fully updated to Mac OSX 10.8.4, all other software is up to date). Multiple users can login remotely to use the machine. Whenever someone logs in remotely, the ...
4
votes
0answers
2k views

Reading out the SMC

A common troubleshooting advice is to "reset the SMC!" But it is actually a bit unclear why and how this fixes things up. Apple also only lists a few symptoms in: How to reset the System ...
7
votes
2answers
8k views

How can I prevent Mac terminal ssh from disconnecting when the screen is automatically turned off?

I frequently use ssh on my MacBook to connect to other servers and run long-running commands there. When I do this, I leave the lid open to let it run, but then if I don't go to make coffee or ...
7
votes
2answers
14k views

Removing the sleepimage file in /var/vm in macOS permanently

I run high sierra, and the large private/var/vm/sleepimage file has been bothering me. My computer has 16 GB of ram, which means sleepimage takes up 16 GB on my drive. I have read tutorials on how to ...
7
votes
2answers
2k views

What is the difference among the various event schedulers for OS X / Darwin?

I'm confused about the differences among the three (that I know of) tools for scheduling running of code on OS X / Darwin: cron launchcd pmset I understand that cron is largely deprecated, but it is ...
2
votes
2answers
2k views

Install 1.69f4 (SMC 1.7) on MacbookPro8,1 running Yosemite

Dec 2018 Update: I bought a new battery (A1322) in Sep 2016 for S$42 because my battery deteriorated further. My MacBook recognised the battery and it had no random shutdowns for a while. However, it ...
8
votes
2answers
8k views

MacBook discharging while plugged in under load

I have the latest Retina MacBook Pro MacBookPro11,2 I quite often have the CPU at about 400%-500% usage (e.g. 4-5 cores at 100%) and also do GPU intensive tasks. While this is happening, the battery ...
8
votes
1answer
5k views

What can cause the SMC to repeatedly need to be reset?

I currently have a problem with my MacBook Pro where the SMC keeps getting screwed up and needing to be reset. The result is always that my keyboard and trackpad become useless, and I have to use an ...
3
votes
2answers
3k views

SSH to Macbook works when lid closed (and plugged in to power)

I noticed that my PuTTY session to my MacBook (which is now on Mavericks 10.9.3) seems to stay alive with the clamshell closed so long as the power cable is plugged in to the laptop. This can be seen ...
2
votes
1answer
925 views

Can I configure a task to run while my MacBook lid is closed?

Can I use pmset or a utility like Power Manager to have a task (such as an arbitrary script or backup) run at a specific time while my Mavericks MacBook Pro's lid is closed? Are there perhaps pmset ...
1
vote
1answer
2k views

CPU System agent core (TC0E/TC0F) running very high

When my MBP (Retina, 13", Early 2015, identifier MacBookPro12,1) is under load, could either be CPU load or "bus-load", ie wifi, usb, webcam etc the CPU System Agent Core-sensor shows a very high ...
6
votes
2answers
8k views

High fan speed and CPU temp with low CPU usage?

I've been having intermittent fan speed and high CPU temperature when my CPU usage is nearly 0%. I don't run any weird apps. If I put my computer into sleep mode and wake it back up, this fixes the ...
4
votes
2answers
26k views

MacBook Pro won't power on after SMC reset

Some water was spilled on the table and came in contact with my wife's Mid 2009 MacBook Pro near the MagSafe adapter causing the MBP to shut itself off. Based on some recommendations from the internet,...
3
votes
1answer
1k views

How to enable “Click-to-play” in Google Chrome Version 43.0.2357.124 (64-bit)?

I run Google Chrome Version 43.0.2357.124 (64-bit) on OS X Yosemite. I want to enable Click to play option, mainly because I would like to lower the power usage of Google Chrome and Google Chrome ...
3
votes
1answer
14k views

How can I force my laptop to shut down when I close the lid?

I'd like my Mac laptops to shut down completely when I close the lid. This is partly for convenience and partly for security reasons. I couldn't find a way to do this in the System Preferences (OS 10....
2
votes
1answer
1k views

How to diagnose the SMC?

This article from the Apple Knowledge Base: Reset the System Management Controller (SMC) on your Mac describes very well which kinds of events are symptoms which might be related to an SMC in need of ...
1
vote
1answer
1k views

Is it possible to “shut off” battery charging in OSX [duplicate]

Is it possible to "shut off" battery charging in OSX with an application rather then physically. Could this be done with AppleScript (I doubt it) or will need to be obj-c cocoa application? ...
1
vote
1answer
1k views

MacBook Pro won't put external display to sleep when idle

I have a Mid-2015 MacBook Pro running High Sierra. I mostly use it as a desktop, in clamshell mode with an external monitor and keyboard. I just replaced the 24-inch LG monitor that was connected ...
1
vote
0answers
152 views

Something is corrupting my SMC, why or what changes the SMC settings?

I asked a question that led up to this: Raise/lower brightness is extremely slow It works just fine after SMC Reset. But the next day same problem. It appears that the problem is that something is ...
1
vote
1answer
416 views

How to change “Automatically reduce brightness before the display goes to sleep” in Yosemite?

A few OS X releases ago, there was a checkbox in the Energy Saver settings for "Automatically reduce brightness before the display goes to sleep". This doesn't appear to be there any more, and hasn't ...
1
vote
1answer
932 views

Preventing iOS devices from sleeping

Is there any straight forward way of preventing an iOS device from sleeping? The only way I found so far is to open the "Music" app and start playing (and muting the volume if I don't really want to ...
1
vote
1answer
3k views

How to downgrade SMC firmware

I have a MBP 6.2. Some time ago (1,5 year I guess) I have installed latest Mountain Lion upgrade and my WiFi (airport) stopped working. Tried many options, spent lot of time on different forums, did ...
1
vote
1answer
281 views

MacBook Pro (late 2013) w/ Yosemite & FileVault won't boot: LCD light only, no other activity

After lid-sleeping my machine with ~10% battery left, a few hours later, attached to AC power, it would not wake from lid-open, keypress, or short power-button-press. After doing a long-power-button-...
1
vote
1answer
214 views

Force MacBook to drain the battery while connected to charger

I leave my MacBook Pro on my desk nearly all the time, connected to the charger with the lid closed, connected to an external display. I've heard this is bad for the battery health, and everyone in ...
0
votes
1answer
56 views

Why does Automatic Graphics Switching keep re-enabling itself without my involvement?

I disable Automatic graphics switching under Energy Saver, as it significantly slows my Macbook Pro (10.15.5). Yet this checkbox keeps getting re-enabled when I have not touched it! How can I prevent ...
0
votes
1answer
1k views

Macbook Pro with abnormal CPU usage and unrecognised battery. How to alternative SMC reset

This Macbook Pro (15" circa 2012) is giving me trouble. After a slight water spill incident, I removed and replaced the hard drive, optical drive and battery (warning sticker ignored). After another ...
0
votes
2answers
4k views

MacBook Pro late 2011 had GPU problems

I have a MacBook Pro late 2011 and yesterday my external screen suddenly showed glitches on the screen; much like the screenshots you see from other 2011 MacBook Pro's that have a failing GPU. As I ...
0
votes
1answer
157 views

Are there any hidden settings to modify default system sleep conditions?

Is it possible in some way to modify conditions when OS X will go to sleep? In my opinion the time delay of system sleep is insufficient. Imagine the situation that we are in the middle of ...