While Eton has made its name with accessories powered by non-traditional methods such as hand cranks and solar panels, the company also makes some traditional battery packs as well. Boost 4200 ($55) is the latest entry in this category, providing a 4200mAh cell inside a slim, black metal housing. Available in black or silver, it’s truly a handsome accessory that feels more premium than it’s price would suggest. A micro-USB cable is included, however Eton hasn’t packed in any Dock Connector or Lightning cords.
Boost 4200’s dimensions are just a bit larger in every dimension than a bare iPhone 5/5s; it weighs a noticeable 30 grams more.
The outer shell is made entirely of aluminum, with a single extruded hexagonal piece as the core, and caps at either end keeping the electronics inside. We’re really impressed with this design, and have been reminded of just how nice it feels every time we pick the battery up. There are two ports, found on the same edge: one micro-USB for power input alongside a full-sized USB port offering 2.1-Amp output.
Underneath a debased Eton logo, there are four battery indicator lights. You won’t find any sort of power button though—the battery automatically starts charging when you connect it to an iPhone or iPad.
To check the battery level, you actually shake the battery; we found a quick flick of the wrist to be enough to trigger the sensor. Some of our editors found this to be a somewhat impractical solution, while others among us didn’t mind it.
Of course, with battery packs charging performance is more important than design. With its 2.1A port, Boost 4200 can charge Apple’s handheld devices as well as its tablets, but more recent iPads won’t go at their full 2.4A rate. We plugged the battery into a fully depleted third-generation iPad, and got to 27% before it ran dry.
