There’s no lack of third-party battery cases for smartphones these days, but the Unity for Galaxy S5 from Unu is a bit unique. While the Unity replaces the stock Samsung battery inside an S5, it also acts as receiver for the native power pack, using both batteries. With a stacked design, the $79.99 battery and case doubles the run time of Samsung’s flagship Android phone.
The secret is the thin part that fits into the smartphone: It contains a 2800 mAh battery that supplements the phone’s own battery, which has the same capacity. The native battery stacks on top of the Unity and the phone simply thinks it has 5600 mAh to work with.
Of course, even a thin, stacking battery will make the phone itself thicker. As a result, you can’t use the standard Galaxy S5 rear cover. That’s why the Unity comes with its own back, available in seven colors, along with an outer bumper that holds everything together. Samsung has typically inserted an NFC antenna in its battery packs but according to Unu, the Unity doesn’t affect the phone’s NFC capabilities.
Bitbitbyte.com recently reviewed the Unity case, saying “If you’re a power user of any sort and can get around the added dimensions the Unu battery case provides (and the neutering of water resistance), this is a hands down must buy.” That’s about the only downside I see: you lose the Galaxy S5’s water resistance with this option.