I've been charging mine on an Anker 8 port "smart charger" we've had for some time, it supports up to 2.4a, and I'm 0-100% in about 1.5 hours (I think like 75-80% in about an hour, then the rate slows a bit).
Next time I do a total deplete, I'll get a more accurate time. Great Anker product, basically handles all our devices at home or on the road (multiple phones, iPad and 2 Apple Watches).