Astro 3 external battery by Anker is the most powerful, versatile and reliable external battery that I’ve come across. It has met or exceeded most of my expectations for such a device. I would strongly recommend it as a travel backup battery for most small electronic devices, tablet and netbook computers.

***** The Specs *****

This 10,000 mAh battery has one DC 5V 1A input, two USB outputs, and one output for a variety of power outlets. The output voltage can be set on either 9V or 12V, although you can also charge devices that take 5V. One of the USB outputs is designed with the iPad in mind, while the other one is intended for Samsung Galaxy S tablet. The specified input charging time is 6-7 hours, and in my own test I’ve verified this to be an accurate estimate. The total number of rechargings is specified to be 500, but for obvious reasons I’ve not been able to test this claim.

***** Battery Capacity *****

At 10,000 mAh, Astro3 is the largest-capacity external battery that I’ve ever tested. It has enough capacity to charge an iPhone or any similar small electronic device at least a three times. For a less power-hungry device (plain vanilla cell phone, Kindle, etc.) you can expect to get many full charges from this battery. The two USB charging outputs have different charging rates, but either one will be able to charge your device in a two to three hours max. I have tested the charger with Morolar Razr, Motoroal Krzr, Amazon’s third and fourth generation Kindle, iPhone 3G, iPhone 4S, and the first generation iPad. It performed more than adequately with all of those devices.

In order to get a good, intuitive feel for the charge capacity of this external battery I subjected it to the “iPad test.” That is, I try charging my first generation iPad form the fully discharged state in order to see how much “juice” am I able to get. iPad is the largest electronic device that I can think of that would still qualify (barely) into the small-electronics category. The verdict: I was able to fully charge my iPad without completely depleting the battery. This is the first such battery that I’ve tested that has passed this test. It took this battery about two hours to charge it to this level. This means that you’ll be able to watch several movies on a trans-oceanic flight and still be able to use your iPad when you land.

***** Accessories *****

The battery comes with a built-in power adapter, two USB cords, and about twenty or so different tips for various small electronic devices. This versatility of adapter heads means that you’ll be able to use this battery with most cellphones and small electronic devices that are popular right now, including all of the Apple’s iOS devices. I wish that the battery came with a small carrying bag or a pouch to put all these accessories in, as I find myself losing these kinds of accessories more often than I care to admit.

***** Design and Build *****

The battery sports a slick cool design, and it looks and feels very modern. It doesn’t feel cheep, and it will definitely not look out of place with the latest and coolest electronic gizmos. It’s fairly heavy, so I’d not recommend carrying it in your pocket, purse or even an iPad case.

***** The Bottom Line *****

If you are a frequent traveler and carry more than one small electronic device with you all the time, or tend to go on longer trips to places without an easy access to a wall outlet (camping, long flights) then this charger is a must for you. It will keep all of your devices charged for a reasonably long periods of time, and it will give you a peace of mind that you’ll never be in a situation where you run out of power. Astro 3 battery is compact and durable, and it will serve well all of your portable charging needs. On the other hand if you don’t need to carry too many devices, or your devices are on the small side, then I’d recommend that you check out either Anker Astro, Anker Astro2 or the Incredicharge I-5000 battery. I find those to be more than sufficient for most of my traveling needs.