If you’re a power-hungry Apple iPhone 5 or 5s user, constantly running out of battery by the end of the day and hunting for a charging solution, you need a battery case. These cases essentially all work in similar ways: They hold a slim battery hidden in the back portion of the case, and the case wraps your iPhone and plugs into your Lightning port. To make the Lightning port fit, battery cases make your encased iPhone longer at the bottom by about 1/2 inch.

The battery case then acts as a portable charger, letting you add some juice to your iPhone whenever you need it.

Battery cases generally work great. The trouble is the extra size and weight. Do you want to take a slim and light iPhone 5s and slap a big case around it?

Enter the TYLT Energi Sliding Power Case

The TYLT Energi Sliding Power Case solves the bulk issue by giving you two cases in one: First, you have a slim and lightweight case with grooves on the sides, and second, you have the battery case “power sleeve” that the first case slides into. Essentially, it’s a case-within-a-case solution.

Sounds bulky, right? Yes and no. It’s not effectively more bulky than other battery case designs that feature 2500mAh-class batteries, but in an instant you can shed the battery case when you don’t need it and go light once again.

I was dubious at first, but I’ve been using the TYLT Energi Sliding Power Case for two months and I’m a fan.

The TYLT Energi Sliding Power Case comes with black and red, blue, or lime accent slim cases.

The TYLT Energi Sliding Power Case comes with black plus red, blue, or lime accent slim cases.

Fit and Finish of the Energi Sliding Case

Included in each retail package are two slim cases, one black and one bright color option (lime, red, or blue). The slim case has a smooth-but-grippy texture with grooves on the side that give it an excellent, tactile grip. I like it a lot. In fact, when the iPhone 6 comes out this fall, I’ll likely buy this same TYLT case because the overall system is so good.

The battery sleeve is a matte black, and it also has a nice smooth-yet-grippy feel. The lines are manufactured with great care. It looks fantastic. I was also pleased to see that TYLT sensibly used a cool-but-understated carved logo on the back, too (I hate gaudy logos on cases).

When you slide your iPhone 5 or 5s into the battery sleeve, the fit is smooth and solid. Never once have I worried that my iPhone would slide out of this case. The TYLT case system is obviously two pieces, but it all comes together with pleasing lines, which, by the way, are only enhanced by the bright, rich color choices of your slim case (lime, red, or blue). Of course, if you don’t like the three color options, you can always go with the included all-black option.

One word of warning: The first few times you take your slim case out of the battery sleeve, it’s going to be moderately difficult, if not a little worrisome. But after you use the case system a few times and remove your iPhone to go light, it gets much easier as it wears in — but still feels solid overall. Like I said, the fit and finish of the TYLT Energi Slide Power Case is just fantastic.

How to Use the TYLT Energi Case

Using the Energi Case is easy. It comes with a Micro-USB charging cable (the standard cable for most non-iPhone smartphones and mobile devices), which charges the battery in the case. It takes a few hours to charge it fully, but as it charges, an LED light on the back button blinks in red to indicate a low charge, blue to indicate a medium charge, and green to indicate a high charge. Once completely charged, the LED indicator light glows a solid green. To check the status, the same colors indicate the rough amount of charge left — for example, blue means a medium charge is left, which means your battery case is 35-to-70% charged. (It’s simpler than it sounds.)

The TYLT battery case system comes with a battery sleeve, a colored slim case (lime, red, or blue) , a black slim case, and a Micro-USB charging cable.

The TYLT battery case system comes with a battery sleeve, a colored slim case (lime, red, or blue) , a black slim case, and a Micro-USB charging cable. Get it at Amazon.

If you have the slider and phone in the battery sleeve and have it plugged in to charge, the iPhone will charge first, followed by the Energi case. And yes, this means you don’t have to rely on a separate Lightning cable to charge the case and your iPhone. Once you have the your iPhone in the case and walking around, the battery drains from your iPhone. Then, if you want to add a little charge to your iPhone, simply press the single button and boom, your iPhone starts charging.

The charge works great, even while using the iPhone. For instance, I could use WiFi to watch Amazon Prime TV shows on the brightest setting (The Glades, most recently) and the Energi case would add charge despite my best efforts to suck it dry.

The Energi will automatically stop charging once your iPhone is full . . . or you can turn it off whenever you want.

And how much of a charge will you get? The 2500mAh battery will fully charge your iPhone with a little juice leftover. For me, the real-world charge seems to be around 1.3-to-1.4 charges for my iPhone 5. TYLT says the case will give you about 9 extra hours of talk time.

(Incidentally, TYLT makes a version of the sliding case for the Samsung Galaxy S4 and S5 — for your jealous Android friends, of course.)

Easy Syncing

While you can sync to your Mac over WiFi, if you prefer the old-school method of syncing by attaching your Lightning cable to your PC or Mac, the Energi Sliding Power Case works great. All you have to do is slide your iPhone out and plug it in. Super easy, and I have no fear about breaking the case by constantly “dismantling” it — because this case is designed to be separated easily.

All in all, I’m a fan of the TYLT Energi Sliding Power Case for iPhone 5/5s for its excellent battery, build quality, and superb flexibility. I’ll be buying one (when TYLT releases it) for my future purchase of an iPhone 6 — no hesitation whatsoever. It’s that good.

Get TYLT on Amazon:

* Note: I noticed that one Amazon listing said the TYLT case worked for the iPhone 5/5s/5c . . . but I believe the title description is in error. The case only works as intended with the iPhone 5 or 5s.

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About the author

Chris Maxcer

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I've been writing about the tech industry since the birth of the email newsletter, and I still remember the clacking Mac keyboards from high school -- Apple's seed-planting strategy at work. I'm a big fan of elegant gear and great tech, but there's something to be said for turning it all off -- or most of it -- to go outside. Online I like to call out cool stuff on Wicked Cool Bite and blog with my buddies at Man Makes Fire. To catch me, take a "firstnamelastname" guess at the url of this site.