I have two Android-powered smartphones in my house: the Virgin Mobile Optimus V and Virgin Mobile Samsung Intercept. If you asked me to describe their battery life, I'd say mediocre and terrible, respectively. In fact, the Intercept barely lasts a day, even with little use. My wife, the one who's using it, is about ready to chuck it in the pond.
I think I've found a way to save it from that watery grave. JuiceDefender is a free app that promises "extra hours of precious battery life." And you know what? It delivers on that promise.
The app works some simple but clever magic: Whenever your phone goes into idle mode (i.e., its screen is off), JuiceDefender disables battery-draining items like 3G and Wi-Fi. Turn the screen on again and the radios spring back into action.
The app also throttles back the CPU and "manages" your apps, though it's unclear in the free version what's being done to which apps. You'll almost certainly want to invest five bucks in the UltimateJuice companion app, which opens the door to a wealth of power-management options and settings.
But even without it, JuiceDefender works wonders--at least on these two phones. At the end of the day, the Android 2.1-powered Intercept was not only alive and kicking, but showing a good 50 percent left on the battery.
As for the Optimus V, which runs Android 2.2, I unplugged it from its charger exactly 24 hours ago. During that time I used it on and off--mostly to fiddle with the app and check the battery. Current status: 81 percent. Without JuiceDefender, it would usually be down to around 60 percent by now.
(Interestingly, the app reported an incompatibility with the phone's ROM, stating it couldn't control the 3G radio. Even so, it delivered impressive results.)
Your mileage will almost certainly vary. And it's worth noting that if you use apps that involve streaming--like, say, Pandora--JuiceDefender may interfere (one more reason to grab UltimateJuice, which would let you tweak the settings to keep Wi-Fi active for specific apps). Same goes for tethering.
Still, if you're unhappy with your phone's battery life, I highly recommend giving JuiceDefender a try. It's free, so you've got nothing to lose.
In the meantime, if you've tried the app yourself, or you have a different recommendation for improving battery life (I've tried app killers, and they don't seem to do much), share your thoughts in the comments.