Sometimes you buy several versions of a thing before you hit on the one that really does what you wanted. This is the case for me with battery packs for my USB powered devices. I included this product in my pre-Lotusphere list of power tech to bring along, but it worked out so well that I wanted to give you a more detailed look.

Portable Power - 10,000mAh rechargeable USB block

($59.99 @ Amazon.com)

What I've wanted is a battery pack I can hook up to my 4G MiFi that will let it run all day long while I'm out doing my thing at a technical conference, then charge up overnight and be ready for another go. By providing my own connectivity, I'm not subject to the unsecure, overloaded, and far from ubiquitous wifi offered by the hotels and convention centers. When I go to Europe, I rent a similar MiFi that comes with a European data plan and use it instead of roaming data on my US based plan. This limits my cost for data while I'm there to $15 a day while providing good connectivity for my laptop, tablet, smart phone, and kindle.

I've tried several products, including a popular model from New Trent that many people recommend and have found all of them wanting until now. Most were too low in capacity to last the day or didn't put out enough power through the USB port to really use the MiFi and keep it charged. Most of the products had both problems.

With the EZOPower unit, I put the battery in one of the side pockets of my day pack and ran a USB cable to the MiFi in the top center pocket. I also sometimes use an extended antenna which I put in the other side pocket. This way, I am my own hotspot and am never out of range. In testing, I connected it to my 4G MiFi at 9am when I left the hotel room, and 9 hours later when I got back to the room it was still running, had 2/3 of a charge left in it, and the MIFI battery was still full. It was finally a "run all day and forget it" battery pack.

Essentially, the EZOPower Ultra High-capacity Rechargable USB Battey Pack is just battery but there are a few features that make it better than any other:

1. Though physically its not too big (about the size of a compact 3.5" external drive enclosure) it packs a 10,000mAh lithium polymer battery.

2. It has two USB power out ports that EACH put out 2.1 watts -- as much as the power adapters for the iPad and Galaxy Tab 10.1. The USB standard is 1/2 watt which is why most of these battery packs don't properly charge and run (at the same time) an iphone or mifi let alone a 10" tablet.

3. One of the USB ports is marked with an "I" for iPad and is rigged so that it tells the iPad/iPhone etc. that it is an Apple charger. The device recognizes it as a charger and pulls the full fast charge. The other is marked with an "S" for Samsung and does the same thing for a Galaxy Tab 10.1 etc. This is the ONLY external battery or charger I've seen which can do this. Both ports also work for anything else I've tried.

4. It is elegantly simple, but has all the features you want. For example, it has lights to indicate it is on or off, charging or not charging, and how much power is left in it. It will also shut off on its own in 10 seconds if nothing is drawing power (preventing it from draining accidentally in your bag).

5. It is attractively built, with a mirrored finish and bumpers on the side. It is compact and solid feeling with no sharp edges and nothing it doesn't need. It has no huge ugly labels or decals.

6. It comes with pretty much everything you need. It charges with 12v DC so along with the small block adapter, it comes with a cigarette lighter adapter to charge it in your car. It also has a DC output port that can push out 9v or 12v and a wide variety of output tips for common devices off that port.

MY ONLY COMPLAINTS with this device are:

-1 : The instructions are written in a nearly incomprehensible East-Asian-English attempt that leaves you scratching your head. Fortunately, there is very little you really need from the instructions to use it properly.

-2 : It doesn't come with a little cloth bag or case to hold it along with the various tips and such that it has. This is easily handled by finding a cloth bag of my own.

I've looked at, and owned, at least 5 different rechargeable battery packs which all claim to do the same job. The EZOPower is the ONLY one I've had that has the reserve capacity, the output power, the port configuration, and the overall design simplicity to really meet my needs.