Well, I went ahead and ordered the Milwaukee fuel, because of all the glowing reports....while on you tube I found this...
https://www.youtube.com/watch?v=A5k0ljHLF58 I tried it on 2 Skill 18v batteries that have been dead for years....to my amazement, it worked! One is at full charge and the other is about 3/4....Tried the old Ryobi's and no go....The B&D battery won't hold the charge for more than a hour.....There are a few more videos that show how to fix or recharge ni-cads ...... hav'nt tried those. New life for shop junk...