Having your smartphone battery die on you just when you need it most has to be one of today's top annoyances, particularly when you're miles from a wall socket. Anker has just released a pocket-friendly backup battery pack with enough juice to charge up most modern phones six or seven times before needing a refill. The Astro3 sports three USB output ports, one of which can auto-identify the connected device and charge it at its full speed.

The Astro3 is not quite in the same league as the yet-to-be-released Powertraveller silverback-gorilla, but it's a good deal smaller and quite a bit cheaper. The 4.4 x 3.3 x 1 in (111 x 86 x 26 mm), 10.6 oz (300 g) unit boasts a battery capacity of 12,000 mAh and has a claimed energy efficiency of 80 percent.

There are no buttons, sliders, knobs or switches to spoil its lines. Instead, the Astro3 is activated with a quick shake. This either starts a dump charge to a connected device or displays how much juice the external battery pack has left courtesy of a circular LED status indicator.

A micro-USB input for charging its own grade A cells sits on top, along with three full-size USB 2.0 output ports. The Astro3 can simultaneously charge three mobile devices, so long as they're not all iPads (the total output across the three ports does not exceed 4 A).

Two of the ports are described as max speed universal ports that are reported capable of charging most devices up to 1.5 A. The third provides full-speed charges up to 2.4 A, using smart chip technology to detect the USB pin signals and identify the device, then auto-adjusting the output to suit.

Though the universal ports feature custom circuitry designed to charge Android phones at full speed, an iPhone will only charge at 0.5 A, so you'll need to make sure the smart port is available if you want your prized Apple smartphone to receive a fast top up. When the Astro3 has finished topping up your smartphone or tablet, it will automatically turn itself off.

The Astro3 ships with a micro USB cable and a 30-pin connector. It has a list price of US$99.99, but is available now on Amazon for US$49.99.

Product page: Anker Astro3