Road warriors want the convenience of having extra juice for their iPhone but don't always want to carry the bulk of an extra battery in their pocket. The $99 Tylt Energi Sliding Power Case offers the best of both worlds, combining a battery that gives you up to 10 hours of endurance with a separate, slimmer case that can be slipped off when you don't need the extra juice.
Editor's Note: An earlier version of this review incorrectly stated that the Energi's battery lasted less time than two other cases. We have amended the results and verdict to reflect this fact,and have given the Energi an Editor's Choice award.
Click to EnlargeWhereas many iPhone battery cases require you to lug around the extra bulk, the Energi's battery can be detached. Unlike the iBattz Mojo Hi5 Power Bank, whose battery can also be removed, Energi's solution is much more elegant. However, it takes a little elbow grease to detach the insert from the battery.
A light inner case clips onto your iPhone, and then slides in securely to the battery section. While the inner case is available in red, green or blue, each Energi case also comes with a black insert. If we were to nitpick, we wish the inner case would be flush with the battery; a small edge that protrudes around the top of the case is a little annoying.
Click to EnlargeThe black battery section has rounded edges and a soft-touch coating on its back, making it more comfortable to hold than the angular Lenmar Meridian. A small button on the bottom lets you activate the battery; an LED in the middle of the button turns green to indicate a full charge, blue when it's half full and red when it's low or empty. We prefer a more precise gauge, such as those on the iBattz and Mophie Juice Pack Helium cases, which use four LEDs to more accurately show the battery level.
Measuring 5.5 x 2.6 x 0.35 inches and weighing 3.35 ounces, the Energi is heavier than the 3-ounce Lenmar Meridian, but lighter than the 3.9-ounce iBattz Mojo Hi5 Power Bank. The Juice Pack Helium is only 2.5 ounces.
The Energi comes with a microUSB charging cable, as well as a 3.5mm headphone extension cable, which is needed if you want to listen to music on your iPhone with the battery pack connected.
The Energi has a 2,500-mAh battery, which the company says will provide up to 9 additional hours of talk time. With the battery case attached, our iPhone 5s lasted 15 hours and 12 minutes on the Laptop Mag Battery Test, which involves continuous Web surfing on 4G LTE on 40 percent brightness. That's nearly 10 hours longer than the iPhone 5s lasts with no additional battery (5:26).
The Energi's runtime is better than the Lenmar Meridian, which provided 10:05 of extra juice and the $79 iBattz Mojo Hi5 Power Bank, which lasted an epic 12:54. The Mophie Juice Pack Helium supplied only 8:40 of endurance.
Click to EnlargeNot only does the $99 Tylt Energi Sliding Power Case offer the best endurance we've seen from an iPhone case--nearly 10 hours more--it does so in a versatile and attractive design. While we wish its battery indicator light were more precise, the Tylt Energi is one of the best iPhone 5/5s battery cases on the market.