modality - a method of therapy that involves physical or electrical therapeutic treatment. rehabilitation - the treatment of physical disabilities by massage and electrotherapy and exercises.
Alkaline AA batteries are rated 1.5 volts, while NiMH AA batteries are rated at 1.2 volts. NiMH generally refers to a battery being rechargeable and to the materials from which the battery is constructed.
Typically a rechargeable solar AA battery declines in performance after a year or so in use. When the lighting time has diminished significantly, you should replace all solar AA batteries. Many manufacturers have found that 1.2 volt NiMH rechargeable solar AA batteries are the best choice for a solar powered AA battery.