Originally posted by wornboots
...By Your formula its time I replace the batts in My Focus 4 I bought in 95 fom TowerH. Its been a good radio all along but I have not used it in the past year either. Thank's for the tip....
Note that the 500 comes from a conservative estimate that cells have a 1/2 life of 2500 cycles (some say 5000 lot more, but I am chicken). Half life means that with normal use, half the cells in a large sample will be dead after 2500 cycles. Since one dead cell can kill your airplane....
I figure that since a new pack is in the 15 bucks range, it's cheap insurance to recycle them after 500. When I was practicing law, I'd cut up the packs and use the cells in my dicataphone and give the remainder to my father in law to use in his mini mag lite.
Anyway don't take my word for it, go to the battery forum and look for links to Red Scholefeld's website. He knows more about Nicads than anyone on the planet and he will even tell you how to build a simple little gizmo from Radio Shack parts that will measure your remaining capacity.
He will also tell you how to use a CHEAP lamp timer to guaranttee that your batteries are always charged and ready to go if you have a chance to make one of those "sneak to the field after work" mid week trips.
Whatever else you may do, have fun flying will ya?