Apple laptops have long had some of the best battery lives of all portables. The company understands just how crucial is a notebook’s performance to real-world usability, and will avoid using impressive-looking components just for the sake of marketing specifications. A high-power graphics processor, for example will reduce battery life to just a couple of hours. See all ultraportable laptop reviews.
There are many ways you can optimise battery life on a MacBook though, to get the longest unplugged runtime. See also: Group test: what's the best ultraportable laptop?
The main CPU is the biggest drain on the internal battery, followed closely by a separate graphics processor if fitted. To reduce the load on the main processor, ensure you don’t have unnecessary processes spinning away in the background.
It takes some experience to spot what’s essential and what’s not, what’s suspiciously high and what’s normal. But if your MacBook seems to be running warm or the fan is conspicuously audible, check Activity Monitor for those runaway processes.
First change the app’s setting from My Processes to All Processes. Then click on the column headed % CPU, to rank processes in order of processor percentage use. If you see Safari running continuously at 50 % CPU or above, for instance, there may be a problem with one loaded webpage. Try closing tabs one by one to find the culprit. If load is still unusually high after closing all pages, relaunch the application.
For graphics intensive applications like games, there’s little you can do to reduce their drain, other than reduce detail settings when playing on battery.
You can help battery life by ensuring that useless webpage elements aren’t taking processor cycles. The best if most severe move is to not install Adobe Flash, which will prevent annoying Flash adverts appearing too. But many sites rely on Flash to show video. Google is reducing its reliance on Adobe Flash on its YouTube site, replaced instead by MPEG-4 through HTML 5, but other sites aren’t always so progressive.
A great alternative to loading power-sucking Flash on every bloated site is to use ClickTo Flash or ClickToPlugin (http://clicktoflash.com). This browser plug-in will show an empty box where battery-sapping ads are supposed to run. And when you need to see content you want, just click to Flash.
The built-in display is the other main drain on battery life after the computer’s processors. Ensure the screen is not set to maximum brightness unless absolutely necessary in outdoor sunlight for example. At all other times, keep the screen as dim as is comfortably possible if you want to optimise your runtime.
Don’t forget the backlit keyboard. The drain will be significantly less the the display, but if you don’t need it, dim it.
Compared to processors and the display, the drain from wireless components is limited but still present. If an ethernet connection is available when travelling, use that rather than Wi-Fi.
When not using Wi-Fi, switch off the wireless from the Finder top menu. The same goes for Bluetooth, if it’s not needed by a Magic Mouse or Keyboard, for example.
Dual-GPU MacBook Pro
If you have a MacBook Pro with automatic graphics switching, which flips between discrete and Intel integrated graphics on demand, use gfxCardStatus (http://gfx.io) to keep an eye on which graphics are in current use.
The free app sits in the top menu, and can be configured to show ‘i’ or ‘n’ for Intel and nVidia graphics, for example. Older GPU-switching MacBook Pro models originally had AMD graphics, and the app works with these too.
If you notice the discrete card unexpectedly in use, click the app’s icon to see which application is triggering the switch. Beware of apps like VLC which needlessly switch graphics away from Intel.
When connecting to external displays the discrete graphics will probably be engaged too. There’s little you can do about this, although in many instances if you’re wired to a display at a desk you’re also more likely to have mains power available anyway.
When using a MacBook on the road, remember that connected peripherals can impose a drain on the internal battery – particularly connected storage drives on USB or FireWire ports that take their power from the bus. Disconnect whenever not needed to conserve battery life.
Finally, remember that wired memory is consuming some power. This will be more an issue if you’re MacBook has lots of physical RAM – 8 GB or more. Try quitting unused applications to free up this memory and reduce its faint power draw.