My 4416B rechargeable batteries need replacement. According to your 4416B instruction manual, 9V 110mAh NiCad batteries are necessary for it. But these batteries are getting harder to find as NiMH batteries are the preferred replacement these days. I have found NiMH batteries, 8.4V 250mAh, to be available. Can these batteries be used in the 4416B Isotron conditioner without any problem? If so, will they charge correctly?