That’s right, $50 nabs you the Anker Astro 3, an external battery with three USB ports and 12,000 mAh, which is — in theory — enough juice to completely charge any iPad.
Why the in theory disclaimer? Because although the Astro 3’s 12,000 mAh capacity exceeds the 11,560 mAh capacity of the battery in the two latest iPads (the iPad 2’s battery is about half that of its successors), there’s always some energy loss when transferring energy from one battery to another.
On the other hand, in this case the loss might be minimal, if Anker’s claims are correct: The company says the Astro 3 is extremely efficient, with a discharge efficiency that’s “10 percent higher than other external batteries.”
The trifecta of USB ports gives the Astro 3 its name (we think), though only one is powerful enough to charge a tablet; the other two can handle smartphones and other hungry accessories.Other nice touches include a ten-stage power gauge and a travel bag.
One caveat: The Astro 3 has no buttons, and instead requires shaking in order to start charging or to see remaining power; vigorous individuals may experience airborne gadgetry.