I have a large Anker battery pack which came with a charger (I didn't want another charger, it just came with it). The battery pack is great, and the charger works fine, but the cable they supplied with it would only charge anything at USB socket currents, no matter what charger you used it with or what device you tried to charge.
It's odd, because otherwise I've always found Anker accessories very reliable. But that cable I just had to throw away.