If your laptop is running out of juice more often than you're finding yourself near a power source, you've got yourself a problem. While there are no new features in Apple's new desktop operating system designed specifically to improve battery life, there are some tried and trusted methods you can use.
Bluetooth glitches can cause a variety of problems, including excessive battery drain if connections are being kept active when they're not needed. You can disable it via Bluetooth in System Preferences (try the options on the Advanced dialog for more comprehensive control over the functionality).
Adjust the Energy Saver settings
If you've owned a MacBook for any length of time then you should be familiar with this screen: Open Energy Saver from the System Preferences dialog and you can adjust how quickly the display dims (the lower the better). The three options beneath can all help you eke out extra time between charges.
Switch your Browser
Despite the best efforts of Google's engineers, Chrome remains something of a battery hog, while Apple says you can get hours of extra use from Safari compared with Chrome or Firefox. If you spend a lot of time in the browser see if going with Apple's native application makes any difference.
Spot the worst offenders
As in earlier versions of OS X, you can click on the battery icon on the menu bar to see which apps are draining your battery the most and shut them down if necessary. The Activity Monitor (search for it in Spotlight) is another way of identifying the most resource-hungry applications on your system.
Update your apps
Applications optimised for El Capitan are obviously going to run more efficiently than older versions, so if you haven't visited the Mac App Store for a while then it might be time to see if any upgrades and patches are available. You should keep El Capitan right up to date as well, of course.
Dial down the brightness
Pushing all those pixels takes up a lot of your battery's charge -- especially on Retina screens -- so reducing the screen brightness is always an effective way of getting more done between charges. Use F5/F6 or the Displays section of System Preferences to see what level of dimness you can put up with.
Reset the System Management Controller
Only try this as a last resort, but resetting the SMC has been a well-known Mac troubleshooting method for years. On recent MacBooks you need to hold down and then release Shift+Ctrl+Option+Power, then start up your laptop as normal -- see Apple's support page on the option for full details.