usually a fast charge is one hour
so your charge rate is the same as your battery size.
however it will usually charge in under a hour because (i hope) you dont run the cells dry.
you could go faster but i wouldnt. if you are useing the plane that much just get a bigger pack.
it's best to slow charge your battery packs, they will last longer (in general)
but i know, we forget to charge them or run them dry at the field.