The Adata DashDrive Air AE400 is switched on by holding the power button up top for a few seconds. Once it fires up, pressing the same button switches between the device's three different modes (wireless data transmission, the default; power bank; and a combination of wireless connectivity for the SD card reader and the power bank). You can tell which mode is currently active by looking at a set of three LEDs with little symbols next to them illustrating each setting.
The power bank’s current charge is indicated by another LED to the left of the three mode lights. It’s green between 100 and 50 percent, yellow between 50 and 25 percent, and red under 25 percent. It flashes when the Adata DashDrive Air AE400 is being charged via the Micro-USB port.
To turn the DashDrive back off, hold that button up top for a few seconds yet again. Powered down, the DashDrive Air AE400 acts just like a normal USB 2.0-based SD card reader. The corresponding LED lights up if you hook the DashDrive up to a PC with a USB cable.
The Adata DashDrive Air AE400 should be able to charge mobile devices like smartphones and tablets on the road using its 5000 mAh battery. Unfortunately, mobile device manufacturers haven’t agreed on a standard for charging their devices, instead sticking with proprietary standards. If they could just reach a consensus, a device like the DashDrive Air AE400 would work equally well with all mobile devices after negotiating how much juice each battery needs. As it is, this doesn’t work.
We tried Adata's DashDrive Air AE400 with Google's Nexus 4, and the configuration immediately demonstrated what we were just talking about. With its 3.8 V, 2100 mAh battery, the Nexus 4 takes longer to charge than if you used Google's bundled adapter. The phone took 40 minutes just to hit 26% charge.