Battery life is estimated at 1 year based on 8 uses per day. The more that the lock is used, the lower the overall battery life. The highest drain on your batteries within the system is the motor that drives the lock mechanism. Make sure that the deadbolt and strike are aligned properly so that there is no unnecessary resistance, as this will make the motor work harder to lock/unlock and will drain the batteries more quickly. Also, make sure that you use all new batteries and not a combination of new and used batteries.