Is there a time limit after which the tag would no longer be usable?
It depends on a number of factors. One is whether the tag only broadcasts when woken up, or whether it broadcasts at regular intervals (which is the case for real-time location systems). I had an active tag on the windshield of my car that lasted for more than 10 years, but I didn’t travel through tolls very often.
If you are using an active tag for a real-time location system (RTLS), you can adjust the interval at which it broadcasts. If you have it broadcast once per second, the tag won’t last nearly as long as if you have it broadcast once per minute or once every five minutes.
If you have a special need for a longer lasting battery, you can have an active tag made with a larger, more durable battery. Obviously, this would add to the tag’s cost.
—Mark Roberti, Founder and Editor, RFID Journal