Do these things run down my laptop battery faster?
May 14, 2015 6:20 AM   Subscribe

I wonder if having 4-5 Word files open (including 2 always, just for for convenience) will drain my Dell Inspiron 11 3000 series battery quicker than just using one file at a time. I wonder: Does more tabs being open in a broswer mean more battery drain? Is a nonactive YouTube tab best being closed till used? I wonder if even having calendar, weather -- stuff I seldom open -- pinned to my taskbar run the battery down more quickly. Same question regarding having several Adobe Acrobat Reader PDFs ready at hand...just comic book pdfs. These things take so little space on the hard drive, so I figure they'd also use less RAM than other actual heavy programs, thus would be easiest on the battery-time availability. Correct me if I'm wrong, but having Foobar, Windows Media Player, and Spotify open at the same time will drain battery faster than having one going, as well as slow things down generally? Add to that the Word, Acrobat, a broswer... Thanks.
posted by noelpratt2nd to Computers & Internet (11 answers total) 5 users marked this as a favorite
 
Best answer: Keep in mind that regardless of file size, the application needed to run the file has to be open, and different applications require more or less resources (memory, processor, etc). Certainly a video playing requires far more resources than a Word document hanging out in the background, though.

Every example you listed certainly utilizes resources and having even a tiny Word document requires Word to run, using processor power, RAM, and thus BATTERY consumption.

Of course having more things open and running, even in the background as the application is thus loaded and running, will drain your battery more quickly. The question, really, is by how much? Some of the things you mention are negligible, but some are significant. If you hear your processor fan kick in and speed up, you can be sure that something is going on that is draining your battery much more quickly than when the fan is idle because all you have going on is a Word document with a blinking cursor.

The idea of having multiple documents of the same time--such as 4 Word documents open--Word is already running and, yes, the file sizes are small, but RAM is constantly being accessed and used more because you have multiple files open, which will drain the battery more than having just one open, but it is enough to be even measurable? I would imagine you would notice a difference.

Oh, and if you want to see how things are running behind the scenes, yes, "there is an app for that."
posted by TinWhistle at 6:44 AM on May 14, 2015


Best answer: So you have two questions...does it use battery faster and does it slow things down.

To your first question, as others have mentioned more things running means faster battery exhaustion. Running computer programs are really never ever completely idle. The Operating System still has to check in periodically with each program and process that is running (While this isn't 100% true, for our purposes you can consider each tab in a modern browser to be a separate process that is running). Now with that said, while this will definitely cause you to use your battery faster it is hard for us to say if you would notice the difference.

As for slow things down, that is a harder question to answer. Your computer is likely far more powerful than what your computer needs are for most daily browsing tasks. Now with that said, one of the ways that your computer maximizes battery life is to purposefully slow things down so that it expends less effort. You'll notice if you plug your computer in and turn off all of the power management features your computer will feel snappier and faster than if you are running on battery and have all the battery saving techniques turned on. It tries to be smart about making the right things be low priority and so on. Not at programs of course always behave which is where you can find a rogue program that causes your computer not to be as efficient as you would like it to be. This is pretty common for some apps on smartphones.

Lastly, I wouldn't necessarily say that there is a strong correlation between small program means small RAM use means small battery impact. RAM usage isn't really driving battery usage. The real culprits of your battery usage is your screen and CPU with spinning hard drives and networking coming up next. Sure, if you had a huge data file open you are probably using a lot of battery but not because of the RAM usage but because the CPU is working hard on that large data set.

In the end, you'll probably get the most bang for your buck by turning down the brightness on your screen. I don't use my laptop on battery power a lot but when I am conferences, low brightness is difference between me running out of power halfway through the day vs after 1 session.
posted by mmascolino at 7:38 AM on May 14, 2015 [3 favorites]


The apps don't affect your power that much. The things that will save the most power is... change to a SSD.
posted by kschang at 9:30 AM on May 14, 2015 [2 favorites]


Best answer: Unless an application is using more than 1% of your CPU time, it is unlikely to have any noticeable impact on your battery life. You can check how much of the CPU each application is using in the Task Manager (press ctrl-shift-escape).

The amount of data an application is holding in RAM does not affect power usage. The RAM doesn't care or even know which of its billions of bits are actually in use by software; it just uses a roughly constant amount of power to continuously refresh and maintain all of them regardless. Accessing memory, reading or writing, does use energy, but that will be directly correlated with CPU load, mentioned above.

Most applications do very little when you are not directly interacting with them. Word, Acrobat, etc. will just sit there waiting for an input event, and their CPU usage will typically be well under 1% in that situation. Web browsers may use more, especially if there are any tabs open that have are running Javascript. That will generally only happen when you're looking at a page, but some poorly-written pages/scripts may waste cycles in the background. Media players, if playing media, will use CPU time. But in any case, you can easily see how much the CPU is active using the Task Manager. If anything is above roughly 1%, it will have some impact on your battery life. If it's under 1%, it really won't.

The same goes for slowing things down in general. If an application is not using much CPU time, it is having little to no effect on how other things run. One exception to that rule comes when your applications have allocated more memory than you actually have physical RAM. Again, you can see that in the Task Manager. If your memory usage is above maybe 80 or 90%, you may run into a situation where the OS starts swapping things in RAM out to the disk, which slows everything down drastically. But if you're under that, there will be no real effect on performance.

In short: Applications use energy only when they're using the CPU, and you can monitor how much CPU time each uses very easily.
posted by whatnotever at 9:42 AM on May 14, 2015 [4 favorites]


whatnotever has it right, and usually you'll know when you're using a lot of CPU - games, video, etc. The biggest exception I've noticed is web browsers can eat up CPU doing (apparently) nothing. This is because it is easy to write bad JavaScript that wastes resources, and a lot of times it is not even the pages themselves, but the ads (or the ad network software) that are to blame. This happens even when the page is not visible. I haven't directly noticed the effect on battery life, but whenever my computer seems to be getting slow for no reason, it's because I left a Bad Webpage open. (for some reason, boston.com is a frequent offender)
posted by mr vino at 10:25 AM on May 14, 2015 [1 favorite]


oh, and if you are running Windows, it used to be that the Windows auto update program was a real CPU hog, and it is frequently set up to run in the background. Not sure if it's still a problem, but you might want to try turning off auto update to see if that helps.
posted by mr vino at 10:26 AM on May 14, 2015


Response by poster: Thanks. But whence the sometimes extreme fluctuation in CPU, Memory, Disk? I opened Windows Media Player and it was a HOG...for a little while, then it backed right down to about 2.5%. Foobar's even better and can hang around at 0%. Sometimes Disk would hit 100% and go red on me. Then all seems to stabilize. Anyway, yesterday the battery seemed to discharge quicker than I'd seen it but things seem on track today -- no real diff. in my apps the past 2 days either. Chalk it up to whatnotever? Right now memory is 67% and the steadiest of all indicators. CPU is at 15-20%. Disk at like 1% (what was its problem 15 minutes ago?). Have only had this pup about a month.
posted by noelpratt2nd at 10:27 AM on May 14, 2015


Response by poster: Is there a way to find what % of my RAM is being used? The machine has 4G.
posted by noelpratt2nd at 10:34 AM on May 14, 2015


Response by poster: On an average hour on battery, I've got Firefox (maybe 5 tabs), Word (2-3 docs), Acrobat, and foobar or WMP running. Also Spotify -- I'll open it now & see how much that takes since it's not drawing on HD memory. Anyway: new lappy, and it seems to use about 20% battery time in an hour. If that sounds OK for what I described, I'm fine.
posted by noelpratt2nd at 10:38 AM on May 14, 2015


You're getting slightly mixed answers here, with both being mostly correct. At a detail level, yes, every single thing you do with your computer is going to make it use more power -- that's just physics. However, what you need to worry about are matters of scale.

Basically, using an app is going to be much more power consuming than just having it open. Further, having, say, Word open with multiple documents will make even incrementally less difference than having just one open. As noted, web browsers can be the exception to this: modern web browsers can be thought of very much as having each tab be a separate program, and yes, there are often very poorly designed sites which can burn you up even when sitting in the background.

For what you're doing, a battery life of 5 hours (extrapolating your 20% per hour linearly) doesn't sound overly bad.

What version of Windows are you running? Unlike the past, newer versions of Windows have generally been more efficient than previous ones for several release cycles, especially when it comes to intelligent use of a machine not on the mains, and also more likely to default to a configuration good for battery use.

Things you might consider doing to extend your life:
  1. Switch to an SSD if you have a spinning disk -- especially if your current disk is "performance" model running at more than the laptop-standard 5400RPM. This will probably be the single biggest change you can make, and will also improve your experience over all.
  2. Turn down your screen brightness to the minimum necessary. Lighting those big, bright displays takes a lot of energy. This is one of the reasons Apple resisted releasing larger phones for a long time -- they didn't want to do it until they could find a way to keep their sexy, thin devices while increasing battery life enough to compensate.
  3. Reduce the number of services that start automatically. Everything that you have that runs in the background -- antivirus, weather widgets, system monitors, cloud backup apps -- consumes additional power. There are apps which will make it easier to see what's starting and disable things you don't need; I'd suggest the free and excellent CCleaner
  4. Run the minimum number of applications necessary. Even sitting in the background they consume at least a little power, and some are poorly behaved and consume alot of power even at idle.
  5. Be careful, though, that you don't end up opening and closing an application that you frequently use. As you've noticed, starting up a program usually causes a high short-term load, and that can wipe out any savings you get from not having it running in the background. Basically, when you're done using it, close it, but don't worry about it until that point.
  6. Make sure you're not using all your RAM, especially if you're switching back and forth between applications. Your system has two kinds of memory: "physical" and "virtual". An application that is active will be using physical memory, but when it goes inactive, and something else needs the memory, it will be moved to virtual memory -- which means writing to disk. This is expensive, as is reading the data from disk when you go back to the app. If you're not using all your RAM on a regular basis, this will be less of a concern.
  7. If you don't already, consider running your browser with an ad blocker, which will help screen out some of the worst offenders on web sites for CPU usage. I'd also suggest turning on whatever click-to-play feature you have available to keep things like annoying flash animations from running until you want them to.
  8. Be attuned to the warmth of your machine. Even if the fan doesn't go on, when it gets hotter, it's using more power. If it suddenly grows warmer, something has changed -- that would be a good time to open your task manager and see what's doing what.
Regarding a couple of your questions:

Applications running in the background may indeed spike the CPU from time to time. Remember the comment above about how even stuff in the background gets some CPU time from now to then. The OS basically says, "Hey, application. You got anything you want to do? if so, now's your time." What happens then can indeed be resource-consuming. There's really not much to do about that, it's just how (modern) multitasking works. You just need to watch for big troublemakers and do something about them.

You can see your current memory usage under Windows in the task manager. Just look at the "Performance" tab.
posted by jammer at 11:49 AM on May 14, 2015 [2 favorites]


Response by poster: Running Windows 8.1. Much thanks. Battery use actually less than that 20%/hr today. Maybe I'm being smarter somewhere.
posted by noelpratt2nd at 12:05 PM on May 14, 2015


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