richrd is correct, they will charge both NiCad and NiMh.  Also, as long as the current they put out (you have to measure it for any unusual applications) is higher than the self discharge current of the battery being charged, the battery will evenually reach full charge.  The reference to www.rcbatteryclinic.com is a good one, very good and reliable info on that site for all kinds of batteries and chargers.