Went ahead and bought Anker 5000ma and 1000ma power banks (from amazon .. got em here in relatives luggage). Happy with the purchase
Hey, heads up. I've had a terrible experience with Anker products despite the generally favorable reviews online and the reasonable presentation of their packaging and CS department.
I had an Astro E3 for about six months before the plastic casing cracked and the lithium-ion pack inside (not Li-Po) swelled dangerously and threatened to burst/ignite. I threw away the battery pack and still have the circuitry, which I may use with another battery pack after some soldering and modding.
Your mileage may vary, but just thought I'd share. It served me very well otherwise, until the unexpected threat of spontaneous combustion reared it's head.
I currently own a "2200mAH" Anker Li-ion Battery that's installed in my Samsung Galaxy S3 i9300. NFC seems to be functioning well, temperature is reasonable, but it's been six months and the battery capacity has degraded significantly, faster than the original supplied battery.
I also purchased an Anker 8A/40W 5-port USB charger (with "PowerIQ") that seems to be very popular on Amazon and is generally selling very well, but mine had four ports dead on arrival. Literally, nothing worked out of the box except for one single port. Similarly, I bought an Anker 24W car charger with a USB port and an attached, coiled microUSB cord that was broken out of the box.
Anker refused to accept warranty claims for all four items because I didn't have an Amazon order ID, and ordered the items through a proxy that refused to disclose the ID, even though they themselves had ordered the items through Amazon.
They seem to have good intentions, but a lot of their products are clumsy OEM products that are also sold by companies with varying different monikers — right down to the packaging and the "PowerIQ" tech.