I’m guessing that quite a few of you do this already, but I’ve found it useful to slap some sort of date on a fresh battery right when you get it.
I’ve got 4-5 ice-electronics units at any one time, so I like to rotate batteries through to keep them fresh and in tip-top condition. Simply enough, it all starts with buying just one battery per year. I put a duct tape label on the battery with the current date, then make sure that one goes in my flagship or primary flasher for the year. The battery I take out of that unit (1 year old) goes into my underwater camera, and the battery I take out of it (2 years old) goes into my spare units. The batteries I take out of those units (3+ years old) I keep charged up throughout the season as spares in case I’m not staying at a place I can re-charge my main flasher battery.
I know that these batteries, when taken care of, will last even longer than the schedule I have down for them. That said, the majority of warranty and service center calls for any ice-electronics are battery-related, so I feel this keeps those problems to a minimum. Pretty cheap insurance, and the best part is that you’re creating spares to always have around. Even if you don’t rotate your batteries through in this manner, it’s helpful to know the exact age of your battery!
Joel