CR123A 3V Lithium Battery for Alarm Sensors High Power Lithium Battery Use for many Honeywell Contacts like the 5816 Should last 5-6 years in a contact It will last 1-2 years in a heavily used door  

12V 7AH SLA BATTERY - NT-12/7 Features: Application/Usage: Security Device Battery Rechargeable: Yes Battery Size: Proprietary Battery Chemistry: Sealed Lead Acid (SLA) Battery Capacity: 7000 mAh Output Voltage: 12 V DC Height: 4" Width: 2...

12V 4AH Lead Acid Alarm Battery Features: Application/Usage: Security Device Battery Rechargeable: Yes Battery Size: Proprietary Battery Size Battery Chemistry: Lead Acid Battery Capacity: 4000 mAh Output Voltage: 12 V DC Maximum Battery Run...