I've been looking at Qi wireless chargers here lately, and every time the subject comes up someone wants to know more about the ZENS charger. We've all heard good things, and often enough that it was evident I needed to get one and have a look. I've used plenty of them, had some varying results, but I had never heard anything bad about the ZENS unit. At ShopAndroid.com, it has a solid five star rating after 26 reviews.
I think I understand why, after using one for a few days.
There's no secret, it's a Qi compatible coil housed in a casing that rests quietly on your desk or nightstand. As long as the Qi standard is followed faithfully (looking at you, first-run Nexus 4 and your weird issues in this area), setting a Qi compatible device on top of the coil should charge it. The Zens charger does just that, but someone put a little thought behind the rest of the unit.
The three popular choices for Qi charging your Nexus 7 or Droid DNA or Nexus 4 each have what's a pretty big flaw to contend with. The cheapest to use option, the Nokia wireless charger (my current choice), doesn't seem to work for a lot of phones out there unless you have it in the tiny sweet spot. Blame it on the phone or tablet, or blame it on the charger, but it's that way. If you have that lucky combo, it works great — but there's a good chance you don't.
The little puck from LG is easy to use, works pretty well for just about everyone, but it has a pair of ultra-brite LED lamps that can get really annoying if you want to charge your phone or tablet overnight in a dark room. You can tape over them, or tear the unit open and disconnect them, or you can just not buy it because it's designed with a silly bright ass blinking light. I swear to God that thing is evil.
The official charging orb for the Nexus 4 works really well, is chock full of HOLO, but everyone knows that getting a phone to stay on it through a charging cycle is a crap shoot. Nobody knows why, and we've heard theories from humidity to the friction coefficient of the material at certain temperatures and conditions, but the fact is a lot of glass-backed nexus 4 phones won't stay on it. The Nexus 7, with it's soft-touch plastic coating holds pretty well, but who know if your next device will?
None of those problems exist in the Zens charger. It's flat, it does have a light (but it's off by default), glows yellow when it senses a Qi compatible device, and glows green while actively charging. And it does all of this at a normal brightness that won't burn your eyes out in your sleep. The unit also senses when a device is fully charged and shuts off the coil to save energy and shut that light off. It's also coated with a nice grippy finish, that combined with it's big charging sweet spot makes it easy to place your device.
It's not 100-percent perfect. It uses a barrel plug and jack for the input instead of a more standard 5v USB input, and that big sweet spot is slightly off center, which is something you have to get used to. But that's it. There's nothing else about this one that I can complain about, and after trying at least a half-dozen of them I'm looking hard for things to complain about.
The unit as-is will charge your Nexus 4, Nexus 7 or Droid DNA right out of the box. There's also a kit with a replacment battery cover for both the Samsung Galaxy S4, and a stand-alone battery cover for the Galaxy S3 by the same manufacturer.
If you're going to invest in a Qi charger, it looks like the ZENS unit is the one to buy.