OmniCel ER34615 3.6 Volt 19 Ah D High Energy Lithium Battery with TabsOmniCel ER34615 Battery is an ideal long lasting power source for gas meters and water meters and is widely. Used in utility metering, alarms and security devices, memory back-up, tracking Systems, SART and EPIRB devices and many others.Lithium Thionyl Chloride has the highest energy density of any practical Lithium battery chemistry, three times greater than Alkaline (Zinc Manganese Dioxide) batteries. It also has the widest operating temperature range of -55°C to + 85°C. Self discharge is low at less than 1% per annum at 20°C, giving an effective shelf life of 10 years.