Quote:
Regardless of what batteries are used in any generation of device why
not install a timer circuit as a quick, perhaps easier to test and prove alternative?
IE Set a timer to offer different ping rates as battery life declines.
7 day's normal rate, 8-20 days 50% rate, 20-40 days 25% rate,
40- end of life 10% just to put a number there.


I am not techologically literature in this field, but here is my idea. I would add a backup battery to start working when the first one dies. The 2nd system should remain in a hybernation mode until some radar/sonar ping is received from a search vessel nearby activates this battery to give pings for only half an hour and then "sleeps" again. I think such device would last much longer.