When people talk smartphones, first comes the bragging and gushing about all the things their pretty new best friend can do. But all that 4G browsing, GPS directions at a touch, uploading photos to Facebook, and talking with friends throughout the day comes at a price: battery life. Ideally your phone will last throughout the day and charge up each night to see the next day at its full potential. But "ideally" rarely happens, so it's good to have a backup plan...a backup battery with an extended power capacity. Here we share 10 different solutions for smartphones for the iPhone 4/4S, various Android handsets, and even a couple popular WP7 phones... For iPhone 4/4S Models Mobius Rechargeable Solar Case: The Solar panel on this case brings a new meaning to charging on the go. 1 hour of sitting under the light provides 25 minutes of talk time or 145 minutes of music on top of the usual amount of battery limitations. The sync slot is swallowed up by the case and is replaced by a micro usb so traditional speaker docks are out of the question. $80 Mophie Juice Pack Plus: The Mophie Juice Pack Plus us good for up to 8 hours of talk time over 3G (16 hours when using a less taxing 2G connection). Got your attention yet? This add-on solution is powered by a 2000 mAh battery inside (adding to the iPhones 4's standard 1420 mAh), protects your phone with a rubberdized, shock proof band (improves grip too), and integrated LED status light gives you the heads up whether you're good to go or it's time to sync and charge again. Other than pushing traditional power more than twice the standard life, the sleek form factor Mophie Juice Pack Plus is arguably the best looking add-on battery case across all phones/platforms, while also acoustically amping up the iPhone 4's audio as a bonus. $99.95 PhoneSuit Elite: For those who value both a strong emphasis on style and functionality (otherwise known as the Jonny Ive philosophy) the PhoneSuit Elite is a serious add-on. Thinner than the previous two options above, while also upping the ante with a 2100 mAh battery, the PhoneSuit Elite's other notable feature is the Quick Charge technology which allows a charge time of just 2 hours, charging up both the integrated add-on battery, alongside the iPhone 4's internal unit. $80 For Android Phones Droidax Power Pack for Samsung Galaxy S II Much like the iPhone battery cases, the Galaxy S II power pack wraps around the phone while offering an expansion of energy. This case is slim and beautiful while adding only 65g to the weight of the phone for 1650 mAh of extra battery power. Talk time increases 7 hours, internet time by 6 hours, movie time by 10 hours, music time by 40 hours and up to 300 hours extra of standby time. $50 Blueshop 1930 mAh Extended Battery w/ Cover for Motorola XT860 4G: This isn't so much of a case as a total replacement of the back cover of the stock back cover for the Motorola model. This conversion kit switches the standard 1540 mAh battery for a higher 1930 mAh for more 'oomph', thus the need for a slighter larger cover to accomodate for the upgraded battery; with the added battery life comes a few more millimeters. We think the trade-off is fine considering what a battery drain 4G devices can be. $70 Hyperion HTC Droid Incredible 2 3500mAh Extended Battery: The HTC Droid Incredible is a solid phone and has spawned several in its image but still manages to stand as a staple of the Android smart phone line. A little shot of power can be administered by upgrading from the 1450 mAh battery to this 3500 mAh beast. The best thing is that the upgrade is probably the most cost effective option on this list. $20 Seidio Innocell 3500mAh Extended Battery for HTC Droid Eris:There are a breed of people who are loyal to their phones and hold out for long periods before upgrading (you know, the ones with duct taped, cracked screen units). We salute you for making your tech last. And for HTC Droid Eris owners looking to extend their Android device's usable life, this battery pack can make boost the out of the box capacity of 1300 mAh to a much more comfortable 3500 mAh, adding 260% to the battery life while only adding 3-4mm to the device's form factor. The battery case is also one of those soft-touch, rubberdized affairs, so it doubles up as a protective case. And we like the battery cells are sourced from Japan, instead of cheaper regions. $65 For Windows Phone 7 Phones PowerSkin for HTC HD7, HD2 & HD7S: The HTC HD7, HD2 and HD7S line has a friend in the silicone encased PowerSkin line (a past Daily Find recommendation), offering their rugged design and additional power to the Windows Phone. The recyclable material creates a thick buffer between your phone and certain damage as well as giving an additional 1500 mAh of life (2830 mAh in total); that's a whopping 300 hours of standby time, while also adding the capability of 360 minutes of yapping time if you still use your phone for voice more than occasionally. The 100% recyclable silicone rubber is pretty large, but it's also pretty grippy, and allows you to (literally) throw your smartphone into your travel bag as a backup and slided on only when needed. $49.99 Verizon HTC Trophy Extended Battery with Cover: Much like the Android phones, many Windows Phones offer a removable battery (an exception is our recent review of the T-Mobile HTC Radar 4G). But in the case of Verizon's HTC Trophy, there's fortunately an option to extend battery life up to a 2150 mAh extended unit with a modified "extended battery door" to replace the stock setup. We like this solution not only for the added juice for a WP7 handset somewhat marred by so-so battery life (PC Magazine reported back just a little over 5 hours, but we experienced more around 6 hours with talk, text and browsing, which still isn't so hot even for a 3G entry level device), but also gives points because the design is a Verizon+HTC solution, instead of an iffy 3rd party design. The $49.99 is quite reasonable too.
Lingosbox 3500 mAh Battery Backup for Samsung Focus: As far as power capabilities of batteries, we think 3500 mAh is the magic number, especially if you can increase battery life at under $20. We're talking about a total capacity which should last well into 2 days for average use with the Samsung Focus' AMOLED screen on automatic (turned off from "high"). This kit is a battery switch with an expanded plastic back to allow space for the bigger battery; considering the original back on the Focus is sort of flimsy at best, the trade out shouldn't affect durability. $15.99