Alarm control unit batteries are rechargeable sealed lead-acid batteries. Battery manufacturers recommend that these batteries be replaced every five (5) years. As these batteries age their ability to provide standby power gradually decreases, hence the 5 year recommendation. Many alarm systems use detection equipment such as motion detectors, smoke detectors and door contacts that have small internal batteries. The life of these batteries depends to a large degree on the amount of motion within their range or the number of times a door is opened and closed. However, these devices monitor their batteries and generally will report a low battery condition and still continue to function properly for at least another thirty days.