PORTER-CABLE 20V MAX Lithium Battery, 4 -Amp Hour Battery (PCC685L)
Back from the dead. Shipping in 1-4 weeks. Front page at this price about a month ago. Will work with Black and Decker tools and chargers with a minor modification:
https://www.youtube.com/watch?v=3QGZFiE
https://www.amazon.com/gp/product/B00FQ8OHJ6/