Whether it happens with that key memo left unfinished, the last scene of a movie unwatched or an epic gaming battle interrupted, it's likely that, at one time or another, you've been left with a dead notebook battery at the worst possible moment. What can you do about it?
"Notebooks are not as efficient as they could be," says Robert Meyers, data center product manager for the Energy Star Program at the Environmental Protection Agency, "and they waste a lot of energy."
The payoff for being aware of how much power your system uses and how to control it can be huge -- because every watt saved can run the notebook that much longer. "The natural incentive is that greater efficiency translates directly into longer battery life," Meyer says.
In this article, I'll go through 11 ways you can cut down on your laptop's power usage. Some may be appropriate for your style of work and/or play, some not; but even if you follow one or two, it could give you those crucial extra operating minutes.
But first, it might be useful to look at which components are the most power thirsty in your device -- and how they are being improved.
What uses battery power?
While there's a lot of variation between an 11-in. Chromebook with an Intel Celeron processor and a 17-in. gaming laptop with an Intel Core i7 Extreme chip, each has a similar array of components that turn electricity into an interactive computing experience.
There are six components that are the major power users in a computing device. They are listed here roughly in order of power use, although that can vary based on the notebook itself. They have each been redesigned over the past decade for greater efficiency, but there's still work to be done.
The processor is a power hog, often using as much as half of the total power in a system. Smaller is better; as the size of the microscopic wires and electronic architecture within the chip shrinks with each generation, its power use declines.
A decade ago, the best Intel processors used the company's 90-nanometer (nm) production process, codenamed Dothan. Today, the company's Haswell chips have 22nm architecture -- less than one-quarter the size and roughly 100,000 times smaller than the width of a pencil point. Chips made with 14nm microarchitecture, a.k.a Broadwell, have been promised for later this year or in early 2015.
Meanwhile, current AMD processors are made using a 28nm process, including the new Karavi laptop CPUs, but the company's Project SkyBridge promises a series of new chips for mobile devices using a 20nm manufacturing process.
2. Graphics processors
Graphics processors are often integrated into a notebook's system, but can significantly drain a battery as well. For example, Intel Graphics 4000 and 5000 integrated video chips typically range in power use from about 15 watts for the HD 4200 at the entry level to upwards of 50 watts for the Iris Pro 5200.
AMD's Radeon graphics engines also vary in how much power they pull. For instance, the mid-range HD 6290 graphics chip consumes about 18 watts at peak use, while the more sophisticated HD 8650G chip uses upwards of 35 watts.
Plus, many high-end engineering and gaming notebooks also have discrete graphics chips with dedicated memory from Nvidia or AMD that can consume a lot of power when they're being used.
Displays have improved -- no doubt about it. The move in the late 2000s from CCFL backlighting to LED backlighting reduced a typical LCD's power drain by about 25%.
More recently, Panel Self-Refresh (PSR) technology can lower power use even further by stopping screen refresh if what's being displayed doesn't change. This can add as much as 20 minutes to a battery's run time, according to Ajay Gupta, director of commercial notebook products at HP. PSR is currently used on a limited number of devices, including the HP EliteBook Folio 1040 and the LG G2 smartphone.
In the long term, display power use could decrease by another 40% by using Organic Light Emitting Diode (OLED) screens that produce their own light and don't require backlighting. These screens are currently being used in phones like the Nokia Lumia Icon.
Traditional hard drives that use rotating magnetic discs are giving way to SSDs that store data on solid-state chips. Solid state storage still costs four to five times what a hard drive goes for, but uses a lot less power.
For instance, the 500GB Seagate Momentus Thin 2.5-in. mobile hard drive (starting at $50) uses 1.20 watts, while a 480GB Crucial SSD (about $236) consumes 0.28 watts, less than a quarter as much. And more lower-cost laptops -- including such lightweight models as the HP Chromebook 11 -- are shipping with SSDs.
According to Gupta, the next step is to stop making SSDs that mimic 2.5-inch hard drives in size and shape, and move to M.2 circuit board technology that puts all the components on a small circuit board, such as the one included in HP's EliteBook 840. This can reduce power use further, he says.
Every watt used inside a computer system turns into heat -- and so the system has to be cooled in order to keep running. The less power used, the less cooling is needed. As a result, current systems that use power more efficiently also use smaller fans that don't need to run as often (and so conserve power themselves).
6. AC adapter
The technology that turns a wall outlet's alternating current into the direct current that a notebook needs has made great strides: From being roughly 50% efficient 20 years ago to between 80% and 90% efficient today. Still, a lot of power is wasted, because for most computers the adapter still draws phantom current after the system's battery is fully charged.
Today, some adapters -- like that of the Lenovo ThinkPad X1 Carbon Touch -- are smart enough to shut themselves off when the battery is full. Hopefully, more are on their way.
According to HP's Gupta, a high-efficiency adapter could be made for a single voltage, like the 110 volts we use in the U.S., rather than switchable between 110- and 220 voltage for global use. Theoretically, it could hit 94% efficiency, he says.
What you can do now
Whether you have a Windows-based system or a Mac laptop, there's a lot you can do right now to make its energy use more efficient and get more life out of its battery. The tips and tricks that follow may not work for every system, but even if you choose one or two, you can make your notebook more efficient.
1. Slow down your CPU
The processor is a great place to save a few watts.
If you're using an older Windows-based system, start with your Control Panel Power Options page, go to the Change advanced power settings section and click on Processor to adjust its maximum processor state. I aim for a balance between performance and power use, and typically set the processor's maximum power use to 95%.
If your machine is recent enough to have a Haswell processor -- and therefore has Intel's Turbo Boost overclocking -- anything less than 100% prevents the CPU from raising its clock speed (and power use) when the computing load increases. In other words, if you want to keep your battery use down, lowering the maximum processor state will add even more power efficiency, even if it takes a moment or two longer to complete some tasks.
Unfortunately, at the moment, there's no easy way to easily disable or control Turbo Boost in a MacBook. Your best bet is an open-source XCode-based command-line tool called Turbo Boost Disabler for Mac OS X.
While you can't easily control Turbo Boost in a MacBook, the Intel Power Gadget can keep you informed.
If you're just interested in how much power your processor is using (including its clock speed and core temperature), you can use the Intel Power Gadget.
2. Add more memory
Regardless of whether you use a PC or Mac, when it comes to performance, more RAM equals better performance and lower total power use. RAM chips use so little power that adding 4GB or 8GB has a marginal impact on its total power use -- more RAM can, however, save power by reducing the system's use of virtual memory.
How? Virtual memory is actually hard drive space that is used to store items from memory when the system runs out of unused physical memory. Because the hard drive uses a lot more power than RAM chips, using virtual memory eats into efficiency and battery time. So adding RAM can not only make your system more efficient, but save battery power as well.
3. Make storage more efficient
Compared to a conventional hard drive, an SSD not only speeds things up but also uses less power -- so you might want to consider upgrading your storage. However, if you can't afford a new drive (or just don't want to bother), a traditional hard drive's hunger for electrons can be tamed by adjusting its power management settings.
For Macs, you can control when the drive goes to sleep in the System Preferences Energy Saver pane. In the Battery tab, start by checking the box that says Put the hard disk(s) to sleep when possible. Apple sets 10 minutes as the default period of inactivity before the drive nods off, but you can tap into the system's pmset utility to adjust it. Here's what you do:
Go to Terminal (which you'll find in the Utilities folder, or you can just search for Terminal). Type sudo pmset disksleep X, where X is the length of time in minutes that you want the system to wait before putting the drive to sleep. (Warning: You'll need the administrator's password to do this.)
The pmset utility lets you set when your Mac's hard drive goes to sleep.
With a Windows system, you can use the Change Advanced Power Settings page in the Power Options portion of the Control Panel.
I generally set my system's hard drive to turn off after 10 or 15 minutes of inactivity. It'll take a second or two for the device to spool up when you need it, but the extra minutes of battery life make it worth the wait.
4. Lessen your display time
Fewer pixels put less of a power load on the graphics chip, video memory and display panel. So although I'm wowed by the latest high-resolution notebook screens, I don't really do much more than view the occasional YouTube video. As a result, when I shop for a notebook, I get the lowest resolution screen that is acceptable for my purposes. These days, that's generally a 1280 x 800 display.
But no matter what the resolution is, a major way to save on battery life is not to have the display running when you don't need it.
For a MacBook, open up the Energy Saver window and adjust the position of the slider control at the bottom marked Turn Display Off After. You can vary the time before the screen shuts down from "never" to as little as one minute.
Apple's Energy Saver window lets you adjust when to turn your display off.
I also dim the screen a bit when on battery power by hitting the F1 button several times until I get to a brightness that is comfortable but not too bright. (If you dialed down too far, the F2 button makes the screen brighter.)
Windows lets you set your power plan for turning off the display and putting the computer to sleep.
With a Windows system, go to the Power Options page and edit the power plan to suit how you work and play. When I'm running the system on battery, I generally set the screen brightness to roughly 80% and have the screen turn off after 15 minutes of inactivity.
Many current Windows laptops also use function keys to make it easier to dim or brighten the screen.
5. Put it to sleep
While you're tweaking your power plan settings, go ahead and set a period of inactivity after which your computer will go to sleep.
How long you wait before putting your system to sleep can affect battery life profoundly. The best approach is to use trial and error to find a balance between battery life and convenience -- for example, my own settings put the computer to sleep after 45 minutes of inactivity. Your mileage may vary.
In a Windows system, go to the Control Panel, click on the Power section and select Change plan setting. Here, you can adjust how long a system will wait before it goes to sleep.
For even more efficiency, EnviProt's Auto Shutdown Manager, a $15 Windows utility, models how you use your computer and can intelligently put the system to sleep and wake it up. It even tabulates how much power has been saved and the amount of carbon dioxide you've kept out of the atmosphere. You can try it for free for 45 days.
And you don't have to wait for the automatic triggers to kick in. Go ahead and manually put the system to sleep if the computer is sitting idle with nothing going on -- by doing this, you can save as much as 15 watts. (Most Windows systems let you press a function key to put the computer to sleep; which one you use depends on your specific system.)
Among other things, Auto Shutdown Manager shows which components shut down when.
You can put any MacBook instantly to sleep by opening the Apple Menu in the upper left corner of the screen and clicking on Sleep. Or you can just close the laptop's lid.
If you want to adjust when your system goes to sleep automatically, go back to the Energy Saver/Battery page and use the Computer sleep: slider control; you can have it sleep anywhere between 1 min. and Never.