It's easier these days than it was in the past to find outlets for charging your mobile devices in vehicles and public places. Even so, you're bound to run into situations where you'll need to nurse the battery in your laptop, smartphone, or tablet because you can’t charge it. Whether you forgot to bring your charger, you're stuck in the woods, or you just want to revel in the untetheredness of it all, here are some techniques for achieving a longer run time.

Increase the run time on any device

Fact: Your battery has a set amount of juice in it, and there's not a darn thing you can do to increase it (safely anyway). Ask Boeing—or Tesla CEO Elon Musk.

So if your device's electrical capacity is finite, the way to make it last longer is to reduce its consumption. And that means turning things down or off, as you do with the lights and appliances in your house. You already knew that, of course—but maybe you didn't know how much stuff there is to turn down or off.

One disadvantage of a sealed phone, like the HTC One and the Apple iPhone, is that you can't swap out an expired battery for a fresh one.

The most obvious battery-draining component that you can turn down—or leave off when it's not in use—is the display. Reduce the brightness as far as you can, and turn it off when you don't need it. Reduce idle period in the automatic shutoff setting. The more aggressive you are about curtailing your display's energy use, the more battery life you'll conserve. If you're in dire straits, manually shut it off as quickly and as often as possible.

The GPS circuitry and the real-time navigation software that uses it are the most notorious power sucks in mobile devices such as smartphones. They stress both the radio and the CPU (with graphics). If you're low on juice, memorize the general location and route, and wait until you're close before you start going crazy with the GPS app. Stick with just the voice cues if you can.

Bluetooth, cellular, near-field communication (NFC), and Wi-Fi radios are other major power drains. Turning these off when you don't need them can double your battery life. Airplane mode, which turns them all off, protects your battery from draining very quickly as your phone continuously searches for signals that don't exist at 35,000 feet. Note: if your phone supports Wi-Fi calling (T-Mobile/Windows Phone 8), using that feature will increase battery longevity, because Wi-Fi radio uses less current.

Finally, though multitasking makes switching between apps quicker, it also consumes more power. Even if an application isn't front and center, it requires the operating system's attention, and it may be performing tasks in the background. It's smart to run only one app at a time when your battery is running low.

Tips for laptop users

So far, everything I've discussed applies to any mobile computing device. But you can do a lot more when the device in question is a laptop. Aside from dimming your display and turning off radios, you can turn off a host of other hardware, such as back-lit keyboards, FireWire ports, Wi-Fi, serial and composite ports, webcams, sound and auxiliary video controllers, and your optical drive (if your laptop even has one). The power savings when disabling any one device might not be great, but disable a bunch and it can make difference.

To disable any hardware component that permits disabling (CPUs and drive controllers don't), type device manager in the Windows find function (by using the box at the bottom of the Start Menu, or simply by typing in the modern interface), or right-click Computer, select Manage, and open Device Manager from the tree on the left. Right-click any item to disable or enable it.

Temporarily disabling devices and services that you aren't actively using can preserve your laptop's battery life.

Now let's dive into the software. I already talked about running only one application at a time, but you may also be running dozens of convenient, but unessential background processes—software updaters, printer and scanner control panels, online storage service apps, and more. To turn off unnecessary processes, use the Windows find function as described above. But this time, type task manager . Alternatively, right-click the taskbar and select Start Task Manager, or press Ctrl-Alt-Delete and select the same item. Once the Windows Task Manager dialog box appears, select the Processes tab and peruse the process names and descriptions.

As a rule, you can safely kill any process that has a third-party brand name in it (such as Adobe, Apple, Dell, Google, or HP). Right-click the program and select End Process Tree to kill it as well as any nonvisible processes that it may have spawned. Don't worry, you're not doing anything permanent here: The process will reappear after you restart or log off and log back in. And hopefully, the time you take disabling stuff won't drain more juice than leaving them running would have. It pays to familiarize yourself with this culling process while your laptop is running on AC power, so you can do it quickly when it counts.

Use the Windows Task Manager to disable processes you're not actively using.

If you wish to disable background apps and processes so they won't automatically return at restart, run msconfig.exe (using the Windows find function). You'll find items you can live without under both the Startup tab and the Services tab. If they turn out to be important, you can always reenable them. For in-depth information and control over how services start (automatically or when required), run services.msc, again using the Windows find function. Uninstalling unused applications is another energy-saving option.

How to boost a battery’s lifespan

The tricks for maximizing your lithium-ion battery's useful lifespan—that is, the number of times you can recharge it before it no longer accepts a charge—are pretty basic. Three things will prematurely age a lithium-ion battery: consistently draining it to the automatic shutdown point, exposing it to heat, and overcharging/overvoltage-charging. That last practice is actually dangerous and can lead to fire or even an explosion.

The number of recharge cycles you'll get from your lithium-ion battery drops with how far you drain the battery regularly. You can get as many as 5000 cycles if you discharge it to the 90 percent level each time, and perhaps only a few hundred if you habitually run it down to 10 percent before recharging. Don't go crazy trying to stay tethered all the time. But you might want to break yourself of the habit of waiting until the low battery warning lights up before you plug in.

The more aggressive you are with your laptop's power plan, the longer your battery's life will be.

Frequently leaving your lithium-ion powered device in a hot car or near another heat source can significantly reduce its recoverable capacity (the amount of charge it can absorb). You could easily reduce a 4-hour run time to 3 hours in a couple of months of such mistreatment. Touch chargers, which are only about 80 percent as efficient as wires, turn the other 20 percent of the supplied energy into heat. Stylish and convenient as they might be, touch chargers can reduce your battery's lifespan.

Avoiding heat doesn't mean that freezing your devices or batteries will make them last forever. In fact, lithium-ion batteries won't accept a charge if the ambient temperature is below freezing. Hybrid and electric cars that use lithium-ion batteries are designed to keep them warm in cold climates. Basically, your battery is most comfortable at a temperature that you probably consider just a little cooler than perfectly comfortable—60 degrees Fahrenheit.

With regard to overcharging/overvoltage-charging issues, you're pretty much at the mercy of the device, the charger, and the battery manufacturer. Lithium-ion batteries come with charge controllers that for the most part prevent overcharging and overdischarging from occurring. But mistakes happen, so if you notice an undue amount of heat in a charger or in the device being charged, stop using it until you find out what's going on. Check with the vendor. If the hardware bursts into flames, quickly move it to an area where it can't set anything else on fire, if you can do so safely, and get away from it. The byproducts of the combustion can be corrosive and toxic.

When storing a lithium-ion battery, try to store it at 60 degrees Fahrenheit and with approximately a 40 percent charge. The charge will prevent the battery from going to sleep and never waking up. This explains why new mobile devices are often partially but not fully charged when you buy them.

The bottom line

It all boils down to this: To extend run time, turn stuff down or off. To extend a lithium-ion battery's lifespan, don't consistently drain it to low levels or regularly expose it to heat. Store the battery at 60 degrees with a 40 percent charge. Batteries are all about freedom, so try to develop good habits without killing the joy.

May your batteries run long and linger longer (and be recycled properly).