It's worth doing the same thing if you ever find yourself out of network coverage – the GALAXY S4, dogged as it is, will keep searching for a data signal. Putting it out of its misery by turning on airplane mode will save you loads of battery life.
Step 7: Background apps
Your GALAXY S4 is great for multi-tasking – the ability to Multi Window a Google search while watching YouTube is nothing short of God-like.
Sometimes, though, you'll have a bunch of apps running unnecessarily in the background, chewing through your battery life like a dog through brand-new shoes.
To close some of those behind-the-scenes power hogs is easy: long-click on the home button to get to the multi-tasking pane of apps, then swipe away all the ones you don't need.
Step 8: Correct charging
The unofficial motto of the SAS, according to trashy action novels, is 'Prior Planning and Preparation Prevents Poor Performance'.
Nowhere does that hold truer than with battery life. The 2,600mAh lithium-ion battery in your GALAXY S4 will perform better if it's treated gently, rather than constantly ravaged.
Try and keep the battery north of 20 per cent; avoid short, frequent charges in favour of full charges once every day or so; and once a month, run the battery completely down, then recharge again. Not only will that increase the day-to-day battery life, but it'll help keep your battery going for the long run.
Step 9: Cool temperature
Lithium-ion batteries don't take well to high temperatures. You'll notice that your GALAXY S4 comes with optimum operating temperatures; those are mostly there for the battery's sake.
In a year of typical usage at 0°C, a li-ion battery will lose about 5 per cent of its capacity. Although we wouldn't recommend keeping your phone in the fridge overnight (we don't want you accidentally pouring it on your cereal in the morning!), it's worth trying to keep it out of direct sunlight, and maybe don't leave your poor GALAXY S4 in the car overnight. It deserves better.
Step 10: Get that GPS out!
The final battery-life trick is probably one of the most important: turn GPS off when you're not using it. The Global Positioning System is awfully clever: it uses satellites and atomic clocks to calculate your position on Earth down to a matter of metres.
But it's also a bit of a battery hog, so you're best switching it off when you're not doing precise navigation – your GALAXY S4 can work out a rough location without it, anyway.
The toggle (between Wi-Fi and Bluetooth on the S4's drop-down settings menu) is the fastest way of whacking it on and off. And then you can enjoy a longer-life battery, and more time away from the plug, to truly make the most of your phone.