There are many different types of active RFID transponders, from a wide variety of manufacturers. Most companies use lithium-ion batteries, but beyond that, it would be impossible to generalize.
Manufacturers typically offer transponders with a battery life of three to five years, but there are applications in which end users require 10 years or more. In those cases, battery size and weight tend to increase.
—Mark Roberti, Founder and Editor, RFID Journal
Is Tracking Cattle Via RFID Expensive? »