The achilles heel of every smartphone on the market these days is rarely the processing power, RAM or disk space, but instead the battery life. Big, bright screens, faster cellular connections and incoming notifications put a constant strain on your device's power reserves, with most heavy users requiring at least one charge per day.

One app that tries to squeeze as much juice as possible out of your device's battery is Deep Sleep Battery Saver for Android, which comes in both Free and Pro (paid) flavours.

The free version lacks some of the customisation found in the pro version, but the app still retains its usefulness. By disabling a slew of options while your phone is in "sleep" mode, the app prevents constant communication with cellular and Wi-Fi networks, choosing instead to "wake up" at set intervals to check unread mail, messages, notifications and other online services. The app stops all background apps and turns of Wi-Fi and 3G whenever the device's screen switches off.

This means processes like Facebook and Twitter won't work in real-time any more, though it might get you through the day without the need to charge your device. Under the free version there are five modes to alter the frequency of "waking up" the device, ranging from "Gentle" to "Aggressive".

Upgrading to the "Pro" version allows you to define custom profiles, differentiate between weekends and weekdays and generally have better control over the app.

Features:

• Turns off services like 3G, Wi-Fi and kills background apps whenever you put your phone in "sleep" mode.
• Wakes up devices with varying regularity to check for email, notifications and other online services.
• Choose the frequency of "waking up" your device.
• Upgrade to pro for more control including custom profiles and settings depending on which day of the week it is.

Check out the Free version of Deep Sleep Battery Saver @ Google Play

Check out the Paid version of Deep Sleep Battery Saver ($1.29) @ Google Play