I was dubious about buying this battery from B-Sky but before I bought the battery I wrote and asked what if I found there was somethig wrong, they replied no problem we'll replace it but didn't give a time limit, I've had this one for 5 months now and have had no problems with it, I also asked on this forum before I bought it had anybody had any problems with DJI refurbished batteries, nobody had.
my 3 original lipos are all exactly the same as the one I bought including all the writing on the battery
on all my OEM batteries it's stated,, max charge voltage,17.4v, nominal voltage 15.2v.
Model No PH3-4480mAh-15.2 v
I suppose some batteries are old as they don't make them any more but as the blurb said some had been returned hardly used, in fact the one I bought had no charges shown using airdata but this might be because when they refurbish them they wipe out all previous info, I just don't know but bottom line is I'm really happy with the purchase and the price
if your concerned about a guarantee why not write to B-sky and ask