ExoLife S4.

Here's a quick look at the ExoLife S4 battery case from Exogear. As the name implies, it's a battery case for the Samsung Galaxy S4 that packs an external 2,600 mAh battery into a fairly svelte case. 

It's a simple enough design. The case comprises as thin front that snaps onto the beefier rear. The phone slides into that rear search and connects via microUSB, just as you'd expect. It's a pretty good fit, and at no point were we worried about the case coming apart. We had no problems with sharp edges or anything like that. Nice build quality. Just make sure you get it snapped in place all the way around.

The business end of the battery case is down at the bottom, with a on/off button and four LEDs to show remaining charge. Press for two seconds to turn the battery case on or off; briefly press the button to see the remaining charge. 

ExoLife S4.

Size-wize, the case doubles the thickness from the phone's 7.9 mm and adds a little more than a centimeter in height. It's not a bad feel in that respect, but it's not exactly stealthy. It's thin, but you'll know you're using it. Our bigger complaint is that the glossy finish makes it pretty slick to hold (to say nothing of the fingerprints). The cutouts and buttons are done well and work as expected.

As is usually the, erm, case with these cases, you're not looking at a high-speed charger. It outputs to your phone at 5V 500 mA, and the case itself charges at 5V 750 mA.

All in all, not a bad battery case. But what it doesn't — and this was the same argument we had with battery cases for the Galaxy S3 — is that you're bulking up a phone when you could double the battery life — and do it cheaper — with a spare battery. It's not that the ExoLife S4 is overly expensive — $80 is about right for this category of accessory. But you can get a spare battery and a slimmer case for a lot less.