Fermaid-K isn't energiser, it's nutrient......
Energiser is DAP a.k.a. Di-ammonium Phosphate.
This is the kind of thing that drives me up the bloody wall.....
2 nations divided by 1 language.
Nutrient usually contains "some" DAP, but a lot of other stuff as well (that yes, the yeast does need), whereas "Energiser" is basically pure DAP.
If you look over at
Gotmead (and have a dig around), there's a calculator to work out how much YANC is needed.
Or you can just check out the
Lallemand/Lalvin yeast chart and while it does say that D47 has low nitrogen needs, it also says that it ferments at "moderate" speed.
Either way, if you worked out what the base dosage of DAP should be for the size batch, then you could reduce it by half or even two thirds - so as not to leave/create any possible off flavours.....
Then see if it speeds up a bit.
Oh and fermentation speed can often be relative i.e. how "balanced" the must was when it started - hence the reports/posts of how some people have had a batch go dry in less than a fortnight etc etc!
Dunno if that's any use.......
regards
fatbloke
p.s. YANC = Yeast Assimilible Nitrogen Content