the iPhone 6, 6+, 6s, and 6s+ will get a 5v @ 2100 ma charge off the ipad charger.
when connected to a standard iPhone charger it only gets 5v @ 1000 ma
here is a new one !
iff you do not run El Capitan , your mac cannot charge the iPhone 6s/6s+ past 5v @ 1000 ma