The proper voltage for AA/AAA alkaline battery is 1.5V. ... The NiMH cells will be providing 1.2 volts throughout it's cycle use while alkaline cells go from 1.6v to 0.9 volts. Alkaline cells have a variable voltage which hardly makes them 1.5 volt batteries when they don't hold 1.5 volts for 80% of it's cycle life.