At the 2014 International CES, we saw a handful of companies taking a stab at the same concept: stackable batteries. The first such product to actually arrive for testing is Lepow’s ADD Power Bank ($50). Like the other models that have been teased, the core concept is the same: start with a small, low capacity pack, and add on more physical parts when you need extra juice. Here, the base is a 4500mAh rectangular battery. A second cell with the same capacity comes along with it, snapping onto the first piece when needed. It’s held in place with magnets. Also included in the package — which is a notably cool bamboo box with a rubber stopper — are a felt carrying pouch and a flat micro-USB cable.
With ADD, Lepow’s designers seem to really have come into their own.
It’s not fancy or flashy. Instead, the system features simple matte plastic rectangles, an elegant look that’s functional, too. The main pack, which comes in blue or pink, stands 4.7” tall, is 2.4” wide, and a total of 0.44” deep. Part of this depth comes from a large rectangle that juts out from one side, serving as a docking system for the second, 4.6” deep, battery. Don’t expect any bells or whistles, such as a flashlight. Instead, ADD has a (supposed) 2.1-Amp USB output, four battery indicator lights, and a micro-USB port for charging, hidden under an arm that swivels out of the way.
The second pack has roughly the same dimensions, although it’s shorter, at 4.4”. This supplementary pack can’t be used on its own as the main pack can, but it does have a micro-USB port for charging independently.
If you’ll be going on a longer trip, or simply need more juice, the second pack easily fits onto the first, and the arm that protects the micro-USB port on the core pack swings out to cover metal contacts on the other. The setup works flawlessly, and is completely intuitive. Even the power light system is smart; instead of two sets of lights, the four LEDs emit one set of colors for one battery, and then another set for the other battery. Instead of pressing a button, you shake the battery to see the remaining life.
For reasons we can’t explain, there’s been a rash of batteries claiming 2.1A output but then falling short of that number, as evidenced by their recharge rates with iPads. ADD is the latest addition to this group. Although it provided an 84% charge to a fully depleted iPad Air — which is 10% better than we would’ve expected and even better than some higher capacity batteries we’ve tested — it took about double the time it should have to do so.
We’re really impressed with almost all of what ADD has to offer.