Updated

Portable smart phone chargers are a fine way to keep your handheld properly juiced, but a case charger that lets you use the device without a dangling, tethered ball-and-chain is way more efficient.

Otterbox can cut that chain with the new Defender with Ion Intelligence case. Available for the iPhone and Samsung Galaxy S III, this case-plus-power source has batteries large enough to fully recharge both devices.

What to know where the Defender with Ion Intelligence gets its smarts? Otterbox’s coming Ion app, which not only tracks both the remaining power of the phone and the case, it also analyzes your smartphone use and determines how best to switch power sources. For instance, the Ion app doesn’t just wait for the iPhone’s native battery to lose its charge. Instead it can activate the case-bound battery when power dips below a certain percentage.

The new Defender case will come in flavors for each of the currently available iPhones, and each case will charge both the reserve battery and the smartphone via a microUSB port. A custom-designed USB-to-microUSB cord that’s expected to charge gear 3X faster than standard-issue wires and supports sync will be included in the box.

The Defender case is a little big, but since it housed a thin, 1450 mAh battery in the back, it’s worth that added thickness and weight. Another reason to appreciate the device is a touch-activated LCD indicator that shows how much juice the Defender packs. Touch the lights, which are located beneath the phones display, and 10 blue LEDs light up. Each light represents a 10 percent increment of remaining juice, so nine lights equals 90 percent. You can also check battery life via the Ion app, but the LED lights are a convenient way to do a quick check without touching the screen.

Look for the Otterbox Defender with Ion Intelligence to go on sale sometime in the first half of this year.