What I was throwing around in my mind as a possibility is replacing the NiCad batteries in some 18 volt drill motors with NiMH batteries and was wondering how I would charge them afterwards. I seem to have ended up with about a half dozen drill motors with just as many bad batteries, but the drill motors are fine. I was reading a thing on the internet about replacing the NiCads in those battery packs with NiNH batteries of much higher capacity, somewhere around 5,000, but was just wondering how to charge them in the future. I have already changed the starter I use at the field with a three cell LiPo and it spins everything up to a nitro 120 engine very well. I would replace the batteries in one of these drills with a 5S LiPo if they weren't so damned expensive. I can buy 15 NiMH batteries with solder tabs and solder them all together for much less than a 5S LiPo.
PS: the bad drill batteries make wonderful weights for weighing down sheet balsa when gluing, such as fuselage sides. Keeps them absolutely flat with no warping, so they are not entirely useless.