There are many factors that influence battery life on the TRU•TEC™ red dot sights. Ambient temperature, intensity level of illumination setting, length of programmable automatic shut-off feature, quality of the battery, these are a few of the factors that weigh in.
We have found that years of battery life (thousands of hours) in constant use, are enhanced by the power saving auto-off feature. We can offer that when set at modest intensity level and shortest programmable run time, 3-years plus is not an unreasonable amount of time for the battery to remain functional. Lowering the level of illumination setting selected can obviously increase this run time dramatically.