Portable Battery Review: Anker 2nd Gen. Astro2 9000mAh Portable Double-USB Port External Battery Charger Review
Editor's Ratings (1-5): 4
What's Hot: 3A combine output power, charges two devices simultaneously, small and easy to carry.
What's Not: The battery recharges very slowly, no power pass through.
Reviewed by Tong Zhang
Anker has been offering portable batteries for smartphones, tablets and mobile devices for a while. Their latest second gen Astro2 portable batteries offer fast charging and two device simultaneous charging features. The second gen Astro2 batteries come in 9000mAh and 12000mAh capacities and they're small enough to fit in any traveler's gear bag.
The Anker Astro2 9000mAh portable battery charger comes in an understated soap bar shape with soft touch matte surface. It measures 4.2 x 2.5 x 1 inches and weighs 7.8 ounces. The battery charger has two USB ports for charging mobile devices and a micro USB port for recharging. All ports live on one side of the battery and there is a circle of LEDs hidden in the front. The LEDs use motion control and they indicate power levels more granularly than most portable batteries this size. It comes with a short USB/micro USB cable for recharging the battery.
The Anker Astro2 9000mAh portable battery charger has a rechargeable Lithium battery that's 9000mAh in capacity. Anker claims the battery features ultra-high energy efficiency and it seems to be true when compared to other portable batteries with the same capacity, especially when it charges smartphones. The Anker Astro2 could charge our iPhone 5 at least 4-5 times and the HTC One at least 3 times in our tests. For tablets, the Anker Astro2 9000mAh performed well also in capacity. The battery charged iPad 4 from 50%-100% and the Samsung Galaxy Note 8.0 from 30% to full with a full charge on the battery in our tests.
The Anker Astro2 9000mAh portable battery charger offers two USB power output ports and it can charge two devices simultaneously. The port marked "Smart Port" can output up to 2.4A and the "Universal Port" outputs up to 1.5A with most devices but it can power an Android tablet. The combined power output is 3A max. The "Smart Port" also can detect the device you plug into it, be it an Android phone, an iPhone or a tablet, and it charges faster based on the device's power input requirement. The Anker Astro2 9000mAh portable battery charger charged the iPhone 5 from nearly empty to full in 2 hours, the HTC One in 3.5 hours and dumped its power to the iPad 4 and the Galaxy Note 8.0 in four hours. While these are very acceptable times for charging your mobile devices, the Anker Astro2 9000mAh portable battery charger itself takes a very long time to recharge. In our tests, it took nearly 12 hours to recharge via computers.
When you connect the Anker Astro2 9000mAh portable battery charger with your mobile device, it should start charging automatically. If it doesn't, give it a quick shake and the motion sensor will turn on charging. The LEDs on the Astro2 indicates power level in 10% increments or reductions, more granular than what we see in most portable batteries. The Anker Astro2 9000mAh doesn't support power pass-through, which means you can't charge your devices connected to the battery while the battery is recharging.
A lot of power packed into a small and relatively light form, the Anker 2nd Gen. Astro2 9000mAh Portable Double-USB Port External Battery Charger can juice up your smartphone several times and fill your tablet at least half if not more. The battery charger is a great choice for overseas flights, long wait at airports or emergency top up for your tablets. The battery has an attractive clean design, easy-to-use motion control and it charges two devices at the same time. The battery itself though takes a very long time to recharge, something you would want to do overnight at least, and it doesn't have power pass-through. If you need something even beefier, check out the Astro2 12000mAh battery charger.
Capacity: 9000mAh Output: 5V / 3A Input: 5V / 1.2A Weight: 250g / 8.8oz Size: 106 x 64 x 25mm / 4.2 x 2.5 x 1.0in