Black and decker 18v cordless is not fully recharging

If the battery is less than 2 years old, Black & Decker/Dewalt has a 2 year warranty on all batteries from date of purchase. Its most likely just a bad or damaged cell from not being fully charged pre-purchase. What happens is most Ni-Cads are only given a trickle charge in the factory and if left on a shelf too long can fully deplete itself, causing irreparable damage to the cells. If you're outside of that, a cheaper solution for battery replacement would be to look into a battery cell manufacturer like Interstate battery, who sells a non-describable battery for pretty much any application for about half the price of a name-branded one. Funny thing is they use the same exact cells. Hope that helps.