This almost makes too much sense.
The problem with protective smartphone cases that feature built-in backup batteries has historically been that they turn your svelte slab of pocketable computing wonderment into a bloated, clunky loaf of electronic jerk bread.
It looks like the fine people at Third Rail have now come up with a fair compromise in the $40 Slim Case for iPhone 4 and the optional $60 Smart Battery add-on. On its own, the Slim Case is a slim case. But its got a spot on its backside into which you can snap the optional battery, should you desire a little extra juice every now and then.
Better yet, you’ll be able to use the battery on future phone models since it’s all an interchangeable system. You’ll just have to shell out for a new case. The battery is rated at 1250mAh—just shy of the iPhone 4’s 1420mAh battery—so you’ll be able to almost double the life of your phone.
Granted, if you used the Smart Battery every day, you’d deal with the same chunkiness that other battery cases provide. But the fact that it’s detachable lets you spread the girth out amongst different pockets and even carry multiple batteries around, too.
I’d personally use the thing whenever I played golf and wanted to fire up my battery-sucking GPS yardage app. That’s just me, though. You might have other activities and accompanying battery-sucking apps in your own world instead. If so, please feel free to take a few minutes and consider whether this product is right for you.
Again, the case is $40 and the battery is $60—but you can buy both in a set for $90 instead.