Get Charged Up About RFID Battery Options

This quick, one-time registration gives you access to members-only site benefits. By Sol Jacobs, Vice President & General Manager Battery Division, Tadiran Electronic Industries Inc. Active RF transponder tags have expanded into a wide range of applications - from asset tracking to automatic toll-paying to wildlife research. While users are - and should be - primarily concerned with the operating performance of system hardware and software, the system manufacturer's choice of battery technology has a direct effect on how long and how reliably that performance is delivered. Each application class has its special requirements for batteries, based on electrical, mechanical, physical (i.e., weight and size) and environmental considerations as well as cost and accessibility for replacement. While the choice of battery technology is often invisible to the end user, a bit of education on battery choices can be beneficial. First, some battery basics: Batteries are divided into two main categories: primary (nonrechargeable) and secondary (rechargeable). As the batteries employed in RFID tags are exclusively of the primary type, this discussion will include only nonrechargeable type. Primary battery types are themselves classified according to the chemical system by which they store and release electrical energy. The major classes are LeClanche (the traditional zinc/carbon/ammonium chloride "dry cell" type), alkaline (widely used in consumer applications), zinc-air (for hearing aids and similar applications) and lithium. The most important characteristics by which these battery types are compared are specific energy (amount of energy available per unit mass, expressed in watt-hours per kilogram), energy density (energy per unit volume, expressed in watt-hours per cubic centimeter), open circuit voltage (the voltage available at the battery terminals when the battery is at full capacity and not supplying current, expressed in volts), service lifetime (the time, in months or years, that the battery can be expected to perform as