Where an AA alkaline battery is 1.5V, a rechargeable AA will be 1.2V. Electronic devices are tolerant at this level, often able to tolerate voltages of 0.9V. Alkaline batteries discharge in a constant and linear manner, where the batteries keep their voltage for several hours before falling rapidly at the end of discharge. Although different, therefore, 1.5V batteries and 1.2V rechargeable batteries are equivalent in use.