Can NiMH batteries be substituted for alkaline batteries?
Usually. However some devices are specifically marked. Check inside the battery compartment of your device or your user manual to make sure they are compatible. Note the discharge curve of alkaline batteries continuously reduces voltage capacity. In fact, over the course of their discharge, alkaline batteries actually average about 1.2 volts. The main difference is that an alkaline battery starts at 1.5 volts and gradually drops to less than 1.0 volts. NiMH batteries stay at about 1.2 volts for almost 80% of their discharge cycle. Once alkaline batteries discharge to 50% capacity, it will be delivering a lower voltage than a NiMH battery.