RE: How do I know NiMH done charging (wall charger)?
I am certainly not an expert on batteries or charging, but I will share what I think I understand about the subject. First off, I have never heard of charging a battery until it gets hot. I always thought that if you are forcing electricity into a battery to the point that it gets hot, you are doing something wrong. Now, about your wall charger. Most of them will have the charge rate printed on them somewhere. Most of them are somewhere between 50 and 100ma. So to make it easy, if it is charging at 100ma, you divide the capacity of the battery (3800) by the charge rate to get charging time. So it would take 38 hours in this case to charge the battery. If your wall wart puts out 50ma, it would take 76 hours to charge fully. In the case of these higher capacity batteries, it might be a good idea to get a charger that will charge at a higher rate.