Most of the iPhone 5 battery cases we’ve tested are assembled in one of two ways: Mophie-style designs bring together upper and lower pieces to enclose the iPhone, while others have you insert the iPhone on a battery-laden sled, then attach a bumper to cover the device’s edges. Tylt’s new Energi Sliding Power Case ($100) is different: it starts with a black battery sled, letting you slide either of two differently-colored ribbed plastic shells into place atop an integrated Lightning connector as needed. Should you want to have an all-black case, you can do that; otherwise, you can accent the always-included black sled with a red, green, or indigo shell depending on the second color you want in the box. It’s a neat trick for quick customization, and though you give up a little protection, Energi Sliding Power Case offers over 30% additional battery power than Mophie’s $120 Juice Pack Plus, and is slightly smaller, too.
From our perspective, the single best asset Energi Sliding Power Case brings to the table is its 2500mAh battery—the highest-capacity single cell we’ve seen in an iPhone 5 battery case at any price. Most of the battery cases we’ve tested include cells in the 2000mAh to 2300mAh range, typically delivering between 90% to 105% of a complete iPhone 5 recharge. By comparison, this version of Energi went well beyond a full 100% recharge, offering an additional 27% of power to hit a total of 127%.
Only the $90 iBattz Mojo Refuel currently delivers considerably more power—208%, split in half between two batteries that you can carry together or separately—for an even lower price.
It’s worth a brief note that while recharging an iPhone 5 with the Energi Sliding Power Case is fairly quick—1-Amp speeds for a roughly two-hour full charge—the 2500mAh battery itself recharges at a slower 0.5-Amp speed, so you’ll need to give it four or five hours to completely refuel. Tylt includes a micro-USB cable for connection to your computer, as well as a headphone port extender; both plug into the bottom of Energy’s battery sled. As with most iPhone 5 battery cases, the headphone port is considerably recessed within the sled’s bottom, but Tylt’s large pass-through hole and extender guarantee that you’ll be able to use any headphones you may have. Speaker and microphone pass-throughs made telephone calling performance basically indistinguishable from a bare iPhone 5, as well.
Tylt’s approach to iPhone 5 protection will go over better with some users than others. Energi’s two simple plastic shells give you the option to pull off the battery sled when it’s not needed—a nice idea—and use your iPhone 5 with comparatively light and thin coverage. Like most shells, Energi’s unfortunately omit drop/shock protection, and don’t offer the top, bottom, and side control coverage found in the standalone iPhone cases we generally prefer to use.
While the bottom is covered when Energi is fully assembled, and the sides are similarly recessed a couple of millimeters within the battery sled, the whole top and the left side buttons are always left bare. Also, the iPhone 5’s screen has less than a millimeter of lip coverage in case of a drop. Consequently, this isn’t the best protective solution for clumsy users.
While we really appreciate the fact that Energi Sliding Power Case delivers more power at a lower price than the Juice Pack Pro, and does so in dimensions that are roughly 1mm smaller on each axis—not larger or boxier in any way—Tylt does omit a couple of frills. Its battery indicator light is a small bar that changes from green to blue to red to indicate diminishing power, rather than the more granular four-light indicators found on Juice Packs. Tylt also skips out on a separate battery indicator button and power switch, blending both features into a single button. While these are common enough issues in iPhone battery cases, we tend to prefer additional lights and controls, particularly for higher-capacity batteries.
Considered in totality, Tylt’s Energi Sliding Power Case bundles an A-level battery with a B-level case—a combination that placed it on the fine edge of our A- and B+ ratings.
