You know what they say about big batteries. But battery life isn't just about size, or necessarily just about the battery at all. The biggest advances in device power are going to come from pairing a big battery with smart software and hardware that conserve juice better than power-hungry smartphones of the recent past.

One new example is Sharp Corp.'s (TYO:6753) newly unveiled Aquos Crystal, which claims a three-day battery life by pairing a big battery with modest specs and hardware. The device includes a (1280x720) resolution display, a Qualcomm Snapdragon 400 processor with a 1.2GHz clock speed, 1.5GB of RAM and 8GB of internal memory -- all features that are now below current standards.

But the next generation of smartphones will do a better job of conserving power without asking users to make sacrifices on speed or capabilities. Here's how:

Software Optimization

Often programs running in the background are the culprits to batter drain, so it makes sense that a solution to battery issues could come from within the software.

Smartphone makers and software developers implement power-saving modes onto their devices, but many have now begun adopting ultra-power saving modes, which take batter conservation to the next level. Such features can be found on devices like the Samsung Galaxy S5 and the HTC One (M8). When activated and a battery is low, ultra-power-saving mode will shut down nonessential functions to conserve battery life, turn a color screen to gray scale, and turn off mobile data and connectivity features such as Wi-Fi and Bluetooth.

Tests have been done to show that the Samsung Galaxy S5 can last up to seven days, using only a few functions and no battery-taxing tasks like Web browsing or video streaming. However, in a more practical setting, the ultra-power-saving mode can ensure a user a few extra hours out of a low battery.

Google Inc. (NASDAQ:GOOGL) has also been working on optimizing its upcoming Android L operating system with an initiative it calls Project Volta. Google claims Project Volta can improve a device’s battery life by 36 percent, while the battery-saving mode that is included can reportedly extend battery life by another 15 percent. Though many details about Project Volta remain unknown, one feature is battery historian, which shows a detailed graph of how a device's battery empties over time and what functions and features contribute to battery usage.

Apple Inc.’s (NASDAQ: AAPL) iOS 8 operating system also is expected to feature software optimization to improve battery life on iPhones. One feature is the usage app, which breaks down how much power various apps and functions consume, similar to battery historian on Android L.

Hardware Optimization

Some manufacturers are building battery conservation right into their hardware. Chipmakers like Samsung Electronics Co. (KRX:005930) and Qualcomm (NASDAQ:QCOM) have put a focus on decreasing the power requirements for its processors, which in turn can increase the battery potential.

Samsung says the technology that powers its new Exynos 5530 chip, which will be included in the Samsung Galaxy Alpha smartphone consumes 25 percent less power than previous chips. Qualcomm chips include components that decrease the power requirements of such activities like cameras, video and sensors on a smartphone without sacrificing quality. Smartphone makers like Samsung, HTC Corp. (TPE: 2498), LG Electronics Inc. (KRX: 066570) and Sony Corp. (NYSE: SNE) use Qualcomm’s Snapdragon chip series.

Spec Configurations

Sometimes the solution to battery issues is not increasing the battery but decreasing configuration of features on a smartphone so they don't use as much power. Many smartphones struggle with battery life because they include features that require a lot of power to function. In particular, high-resolution displays and super-fast processors can draw the most power from a handset. For example, many upcoming devices have displays with QHD (2560×1440) resolution. This means such displays have four times as many pixels as an HD (1280x720) resolution display; they provide brighter images and deeper and richer colors.

Regardless of resolution, displays typically use the most power on a smartphone. However, using features like lower-resolution displays can help conserve battery power on a device. Manufacturers often do this when building basic phones for developing markets. Many basic phones have over 30 days of battery life due to their extremely low-power components. The Aquos Crystal has a 2,040mAh battery, which is not extraordinary, but more than enough to power its lower-end specifications, hence the extended battery life.