I would first like to apologize to our friends at LePow for the very long delay. I suffered a hand injury a few months ago that prevented me from typing effectively until just now. Though I have pictures of the 'accident', they would only be suitable for medical journals, so I'll spare you all the discomfort of having to see what happens when fingers have an unfortunate encounter with a power tool.
The LePow ADD continues in their tradition of environmentally friendly packaging, being shipped in a plain cardboard box which houses a container of... CORK! Yes, cork. Very clever, and very trendy.
Unpackaging the ADD leaves you with rectangular bodies, the main unit and an expansion pack, along with a gray felt pouch and silicone holder which contained a color-matched USB cable. This unit does not have as many 'tchotchkes' as the Moonstone, which is fine by me. I don't need stickers or any more USB drives, I'd prefer that money go into enhancing quality and features.
I'd first like to say that I much prefer this form factor over the Moonstone, because for a business traveler such as myself, it is far easier to pack in a briefcase or even jacket pocket being flat and squared off. The Moonstone, while highly capable, is shaped in such a way that its rounded edges while very fashionable and exhibiting an excellent aesthetic design sense, make it somewhat less suited for business use.
Usage is fairly straightforward. The expansion pack 'docks' onto the main unit much in the way a Lego is stacked on top of another, and is held into place with a magnet. It's easily removable and a bump or drop will dislodge the expansion pack, but the engineering approach is so clever and the probability that the unit will become dislodged in use is so remote, that I overlook that possibility in favor of appreciating the ease-of-use. I mean, really... who doesn't like magnets? How cool is that???
To activate the ADD-on pack, a twist of the aluminum switch block 90 degrees from the main unit brings two embedded spring-loaded pins into contact, activating the secondary unit when the primary unit has expired. Recharging is likewise accomplished the same way.
There are some very cool features built into LePow units, one of which is the ability to tell when your power source needs a recharge itself. In the case of the ADD, an accelerometer (?) will trigger four LEDs to display with a bit of a shake on the unit. Very subtle, and very classy. A nice touch. I don't like a lot of 'bling' on my equipment, and this fits in very well.
Regretfully I'm not an electronics engineer, so I can't comment on the particulars of efficiency, but here is an illustration of recharging an HTC One M7:
10:30AM – 15% charge on phone
11:30AM – 49% charge
1:00PM – 85% charge
1:45PM – 100% charge
So, roughly 3 hours for a full charge from nearly dead. That might seem a long time compared to a USB or AC charger, but when the chips are down, and you're miles away from a power source, this unit can be a lifesaver. For those of you who are 'preppers', I'd suggest keeping a LePow unit in your bug-out bag. Y'never know...
I think anyone would be very happy with any LePow backup power source. Their products have "all the right stuff"... high capacity cells, overcharge protection, ease of use features and solid build quality. A great value all around. However I'm particularly fond of the ADD for the reason stated above. Go get one!