I was planning to use my Li-ion battery tools on putting a car body onto a frame at a shop we were using, and lo and behold, my C3 Craftsman batteries weren't charging, because the charging unit crapped-out. I ordered a new Ni-cad/Li-ion battery charger suitable for Craftsman C3 batteries off our Amazon Prime account, with same-day delivery. It came with two 4 a/hr Li-ion batteries.
It was advertised as being a fast-charger, and so-far it's living up to that. The two-batteries I was attempting to charge for the car work came-back fully-charged in < an hour each, and the two Li-ion batteries that the charger came-with were showing charged to level 3 of 4 when they arrived. I put them in and soon they were showing 4 of 4 LED's. I'll try some work tomorrow, and see what kind of longevity they have. Two batteries and the Li-ion charger were ~$60 delivered, same day I ordered 'em.