It's reasonable to expect your phone to last all day on a single charge, but sometimes it doesn't. And if you're traveling without convenient access to a charger, you can run into real trouble. The battery life of a phone is partially determined by the phone itself -- Apple's new 5S lasted 11 hours in MacWorld's looping battery test -- about 90 minutes longer than the iPhone 5 -- and four hours longer than Samsung's Galaxy S4. Still, Droid Razr Maxx holds the record at 13 hours, 28 minutes. But how you use your phone can drastically affect how long a single charge will last. After downloading iOS7 to my iPhone 4S, I noticed my battery charge was dropping faster than it had before the update. I heard the same complaints from readers. With a week-long conference to cover in New Orleans, I knew I had to make adjustments to my phone, so that I could get through a full day without having to stand at a charging station. I made the changes during a brief layover in Denver, and I'm happy to report they worked. The less you use your phone, the longer the charge will last. But even when your phone is idle, many items may be running in the background, consuming precious battery life. The trick is to eliminate or reduce these invisible operations. Here's what you can do to get more active time from your phone, whether it's an iPhone or another type of smartphone. (I've included directions for those using iOS7, so you'll have to modify them for Android and others.) The most effective adjustments you can make are to dim the display and turn off auto brightness. Open Settings from the home screen and select Wallpapers & Brightness. Use the slider to dim your screen as much as possible. Toggle auto brightness to off, so your phone will not work to adjust the screen to surrounding light. While you're here, you can also switch from a dynamic wallpaper to one that is still and gain a bit more battery life, since the phone is not using energy to support an animated image in the background. Tap the screenshot of the default wallpaper to open up additional choices. Choose Stills to select an available image or Camera Roll to use your own still photo. Regularly close inactive apps. It's easy to forget about apps that you've opened. Each time you make a call, send a text or search, these applications and all others remain open. Double tap the start button to see a row of icons for each open app, along with thumbnail images (Apple refers to these as cards) of the last pages you viewed in the apps. To close them, swipe the cards from the bottom to the top of the phone as if you were wiping it off the top of your display. Apple has added a lot of animations to iOS7. The swooping in and out as you navigate apps consumes power. Turn off these motion effects by going into Settings, tap General and then open Accessibility. Scroll down to find Reduce Motion, and in this case, toggle it on. Return to General. Before leaving this area, turn Siri (Apple's voice assistant) and Background App Refresh off. This is also the area where you can curtail your phone's search activities. iOS7 has been programmed to search a dozen different types of items, including contacts, music and games. If you don't use some of these things, you can turn Spotlight Search off. From General, tap Spotlight Search and then tap to uncheck items that don't require search. Next, turn off push notifications, which are the alerts that appear at the top of your screen. With push notifications on, your phone is constantly searching for new activity and draining a bit of power. Go to Settings and then open Notification Center. Scroll down to find Include, which displays a list of apps that provide notifications. Tap the arrow to the right of each app and then select None for those you can live without. Many apps use location services based on your phone's GPS, which also runs down the battery. But not all apps need them. For instance, you may not want each photo you take to be tagged with a location. You can turn location off for specified apps opening the Privacy section in Settings. Make sure your Auto Lock interval is set to one minute, the shortest amount of time available between your last interaction with the phone and when it goes dark. You'll find this setting under General. Finally, if you're caught off guard and notice your battery has sunk to 10 percent or less, switch to Airplane Mode. Most phones have this feature, which shuts off the device's transmitting function -- no calls or texts or packets of data can come or go from the device. This way, you can reserve just enough battery to make an emergency call or send a text. Leslie Meredith has been writing about and reviewing personal technology for the past six years. She has designed and manages several international websites. As a mom of four, value, usefulness and online safety take priority. Have a question? Email Leslie at email@example.com.