Questions tagged [power]

The electricity drained by a device

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111
votes
6answers
137k views

How can I keep my Mac awake AND locked?

I want to leave my Mac awake overnight so it syncs 4GB of data from Dropbox. I need to prevent the machine from going to sleep because that pauses the Dropbox sync I've been using Caffeine to keep ...
68
votes
10answers
149k views

Can I use 45/60/85W MacBook chargers interchangeably?

I have a 13" Macbook Pro that came with a 60W power adapter and a 15" Macbook Pro that came with a 85W power adapter. Can I use either adapter with either laptop? There seems to be disagreement in the ...
52
votes
12answers
82k views

How can I avoid my MacBook Pro giving me minor shocks?

The aluminum Macbook Pro gives a mild shock when connected to a wall socket and charging. It only happens when I'm, for example, not wearing shoes or slippers and my feet are resting on the ground (i....
39
votes
5answers
17k views

Turning Power Chime Off

On new Macbook Pro, Power Chime runs. Whenever I delete from core services it comes right back. It makes a sound when plugging in your power cord even when the volume is at 0%. The solution I have ...
39
votes
10answers
128k views

What would happen if I use a power supply with a different wattage than the system is designed for?

My girlfriend has a Macbook Air. The power supply is smaller and lighter than the Pro. It has an output of 14.85V and 3.05Amps. My Pro Retina has a power supply that is 20V and 4.25 Amps. Both ...
39
votes
4answers
19k views

Use caffeinate to prevent sleep on lid close on battery

The native caffeinate utility is not working to prevent my macbook from sleeping when I close the display. Instead, the system sleeps and various network services ( VPN, screenshares, VOIP calls, ...
29
votes
5answers
62k views

Is it OK to charge my iPhone with my iPad charger?

I have an iPhone 4 and an iPad. Since the iPad really charges best off the wall charger I keep it plugged in, but I usually just charge the iPhone off the computer. Although frequently if the iPad ...
23
votes
4answers
22k views

Why does GPS on the iPhone use so much power?

I keep reading in articles that GPS on the iPhone, or any cell phone for that matter, uses a lot of power, but I've never heard an explanation of why. Why is this? The phone doesn't have to transmit ...
21
votes
12answers
35k views

How to retrieve current wattage info on OS X?

Is there a way to retrieve the current watt usage info on OS X Snow Leopard? I'm using mid-2010 iMac, so I'm not looking for just battery-related apps. Does OS X even monitor power usage? Do I need ...
20
votes
7answers
29k views

iPad displays “Not Charging” when plugged into USB ports. What can I do?

When I plug my iPad into my computer's USB ports, the iPad battery area displays "Not Charging". I understand the iPad requires more wattage to charge compared to an iPhone or iPod, as evidenced by ...
20
votes
4answers
22k views

How to monitor USB power consumption?

I'm looking for a way to monitor the power being drawn from the USB ports on my Mac. System Profiler doesn't appear to display this and I haven't been able to find any applications or tools to do the ...
17
votes
4answers
10k views

What's the point of the 60W Apple MagSafe replacement charger?

One of the cable tabs on my MagSafe charger for my MacBook came undone, so I took this as a sign to retire the charger to home use and to purchase another for travel. When I went to my local Best Buy, ...
14
votes
3answers
16k views

What are the consequences of using a low-wattage USB-C power supply with a MacBook Pro?

This question pertains to USB-C not MagSafe. MagSafe negotiates available power with the Dallas 1-wire protocol. USB Power Delivery (PD) is an unrelated protocol. Answers based on experience with ...
14
votes
3answers
3k views

How does Apple calculate the energy consumption of a process in OS X Mavericks

In OS X Mavericks you can monitor the energy consumption of different processes in Activity Monitor. Here we can see 'Energy Impact' and Avg Energy Impact' and that the values can exceed 100. Also ...
13
votes
3answers
16k views

Force “low power mode” on mac

When there is less than 5% battery left on a mac, the battery indicator goes red and system performance significantly drops - presumably in an attempt to make that remaining 5% last a little longer. ...
13
votes
3answers
4k views

Can I restore pre-Mavericks power key behavior?

Mavericks changed the behavior of my MacBook Air's power key to put the Air to sleep immediately when pressed briefly. Prior to Mavericks, the power key would summon the Shut Down dialog. As ...
13
votes
4answers
61k views

Can i use my old MacBook charger on my new Mac?

I have a 2011 15" MBP, that uses a 85W power supply. My old 2008 MBP 15" also has a 85W power supply, but I cannot get it to work. Shouldnt it? Its the same watt power, and the adapter fits.
12
votes
2answers
6k views

Should I use the adapter or the battery?

I want to know when my MBP's battery was fully charged it's better to unplug my adapter and use my battery power or still let use adapter power? I somewhere read that when MBP's battery was fully ...
12
votes
5answers
55k views

Keep iPhone Screen On (when plugged in)

Is there an app (normal, jailbreak) that will keep my iPhone (3GS, OS 4.x) screen on, indefinitely, when it is plugged in, regardless of what app is running in the foreground?
11
votes
1answer
122 views

How can I find out which USB Type C port is supplying power

I have a MacBook Pro 15" Late 2016 with USB-C ports. I also have a LG 27UD88 monitor that can supply 60W, and a CallDigit Dock that can supply 90 W. But still sometimes the MacBook is at 0% battery, ...
11
votes
1answer
289 views

Macbook started to consume battery more quickly

This seemed to happen after I did several things at once (all of which I have since reversed in trying to track this down): installed a (Crucial M4) SSD drive (replacing my old SATA 5400 RPM drive), ...
10
votes
2answers
958 views

Why can my Mac charge my iPad but other computers can't?

What do Macs do differently so its USB ports can charge my iPad, but if I plug into a USB port on my PC I get the "not charging" message?
10
votes
5answers
6k views

Can I charge a 2017 MacBook Pro with a third-party USB C power adaptor?

I've got a 2017 MacBook Pro which comes stock with an 87W USB C Power Adapter. I want to purchase an additional power adapter, but I don't require an official Apple one. I notice that Anker make one ...
10
votes
4answers
16k views

What is the iPhone's standby policy regarding WiFi and 3G?

I have an iPhone 4s with the latest iOS. It seems that when I wake it up from standby, it switches from 3G (or EDGE) to WiFi. Judging from that, I suspect it turns off WiFi when in standby, and only ...
10
votes
2answers
151k views

Is it safe to use my US iPhone/iPad charger with a simple European plug adapter?

I'm using the US wall adapter that came with my iPhone to charge it: When I travel to Europe, is it safe to use this with a simple US-European adapter, or do I need a transformer or some other device ...
9
votes
2answers
15k views

How to reset a magsafe charger that doesn't charge macbook pro's battery?

I have a Magsafe charger (original) that doesn't charge my MacBook Pro's battery. When it is connected, it will allow the machine to switch to power adapter mode (meaning no battery consumption) but ...
9
votes
4answers
8k views

Does an iPad consume more battery power when there are multiple applications open?

Does an iPad consume more battery power when there are multiple applications open compared to let's say, having only one application resident in memory? If there are differences between the ...
9
votes
2answers
38k views

How do you check how much current a Mac USB port can deliver?

This question is similar to the superuser question "How to check how much power a USB port can deliver", which is answered for Linux and Windows. How do you check the same on a Mac?
9
votes
4answers
146k views

How do you get the Apple Watch out of Power Reserve mode?

I got it into power reserve but can't figure how to resume normal mode. I have tried tapping and pressing the screen and holding both side buttons.
9
votes
4answers
39k views

Can I (or should I) use a MacBook charger on my iPhone?

I recently got a MacBook with the USB-C charger. It comes with a 29-watt power brick, and I was wondering if I should use this to charge my iPhone. I've heard that the iPad power brick (I think 10 ...
9
votes
1answer
9k views

Phone-only mode on iPhone

Is there a way to switch the iPhone’s functionality to a phone-only mode. In this mode only incoming (and possibly outgoing) calls and SMS messaging would be activated. All other services (location, ...
9
votes
6answers
56k views

“USB device drawing too much power” error on startup with no devices connected

Since upgrading to Lion, I get this error every time I start up: I've read the answers suggested here, but they seem to indicate that it's the presence of a second device that's causing the problem. ...
8
votes
3answers
1k views

iPhone SE powers on whenever moved, defective? [duplicate]

Got a new grey iPhone SE for Christmas from the Verizon store. Seems to work fine except for one issue. When the phone is off (standby), any sudden motion turns the phone on, as if the home or power ...
8
votes
1answer
3k views

How does the iPhone know it's not using an Apple cable?

Sometimes when I plug a cable in to charge, the iPhone says it may not work with this device. How does it know it's not an Apple cable?
8
votes
1answer
20k 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
3answers
9k views

Which uses more battery when tethering - Wifi or BT on iPhone 4S?

I'm not really bothered which is quicker - I'm guessing this is wifi anyway. I just want to know which would allow me to get the most life out of my iPhone 4S when tethering to it with may MBP. Thanks!...
7
votes
3answers
22k views

“Battery not charging” on MacBook Pro

I have the infamous "battery not charging" problem on my 2014 Retina MacBook Pro. The power source shows as "Power source: power adapter". I checked system info and I have 1100+ cycles, which I guess ...
7
votes
3answers
40k views

Does closing the lid put a MacBook Pro to sleep? Would it hurt the computer if I carry it around without shutting it down?

When I first got my MacBook Pro, it took less than 30 seconds to start up. Now, after several months, it takes about two minutes to startup and I can tell that it is not as responsive when using some ...
7
votes
1answer
792 views

Are Macbook Pros with a rusted / corroded MagSafe port safe to operate?

So I have MacBook Pro 13" 2015 and when I connect the MagSafe power connector to it, it seems like it’s more difficult to charge. So I check the MagSafe port and want to clean it I think. When I ...
7
votes
4answers
9k views

Using my iMac in a country with a different power supply standard

We may be relocating to a different area of the world where the power standards and outlets differ considerably from what I've got here in North America. Is the power supply in my iMac auto-adjusting,...
7
votes
1answer
472 views

How to select power direction over USB-C

I have a USB battery which has a USB-C port on it. When I connect it to my MacBook Pro (regardless of whether the MacBook Pro is running off its battery or via the mains), the Mac doesn't charge the ...
7
votes
1answer
5k views

Easy way to disable processor cores on the fly

Hey i'm looking for a fast way to disable processor cores of my macbook to save power when i'm stranded away from a charger. I'm away that instruments can do this from it's preferences, but that's a ...
7
votes
1answer
4k views

Does powertop work with Mac OS X Snow Leopard or are there other power profiling utilities?

I recently came across a blog post highlighting powertop for Linux (see: http://www.lesswatts.org/projects/powertop/). Based on the FAQ, powertop relies on the fact that the Linux kernel is now ...
6
votes
2answers
17k views

Monitoring power consumption on Mac

The Android OS monitors the power consumption of running apps and hardware (display). As you may guess, this is a useful feature as it allows to track down energy greedy apps. Is there an application ...
6
votes
2answers
2k views

2016 Macbook Pro 15" In Flight Power Solutions?

I travel a lot by air and have run into a problem with my 2016 Macbook Pro 15": it draws too much power for in-seat charging on United Airlines (75 watt max). Since my journeys have me in transit up ...
6
votes
8answers
42k views

Best replacement for MacBook Air MagSafe 2 cable (OEM or 3rd party?)

My MagSafe 2 cable for my 2012 MacBook Air stopped working. Took it into Apple store where I had bought my MacBook Air, and sure enough it was the excessive cat chew marks that had degraded it*. Can ...
6
votes
1answer
2k views

Is there a way to get the OSX battery icon to display both percentage and time?

I am working on a 2006 MacBook with Snow Leopard. The battery level indicator has the option to show Time or Percentage remaining. I would like to show both. Is there a way to enable this? or Can ...
6
votes
5answers
59k views

Is it possible to charge my MacBook Air from a powerbank?

I recently bought a powerbank that has two USB outlets. It's great for charging my phone and iPad. Is it possible to charge my MacBook Air from the powerbank? If it's not possible to do this "out of ...
6
votes
3answers
22k views

How do I locate applications that drain my battery on a MacBook Pro?

I purchased a new Macbook Pro and have since downloaded a ton of applications and add ins. I think some of these apps are responsible for draining my battery too quickly. How do I identify what ...
6
votes
2answers
13k views

Does having Bluetooth enabled draw extra power when no devices are connected?

I generally turn off Bluetooth on my Macs and iOS devices when I'm not actively using a Bluetooth device. My assumption is that this saves battery life, but I realize that I have no fact to back that ...