Why must I replace the beacon’s battery at 5 years when it has an 11 year lifetime?
The battery does not have an eleven year “useful” life; it has an eleven year SHELF life. Once you install a battery in an EPIRB or PLB, current is being drawn when you self test the unit during the 5 year “replacement” life. There is also a minute current (in the micro amp range) being drained from the battery, in the “rest state” of an EPIRB or PLB , during the full 5 year period of the battery’s stated life. The battery is guaranteed to last the full specified period of 24 or 48 hours if activated in an emergency, any time during the 5 year replacement life. When the “replacement due date” is past, the activation period of an EPIRB will start to decline and cannot be guaranteed any longer.
