Between Jerry's post and yours I have learned a lot and have more to think about. Thanks so much.

Just a couple thoughts:

Just thinking out loud here... Depth of discharge means how far into the discharge cycle you let the cells go right? Considering memory, if you only let them go to a specific percentage aren't you guaranteeing memory will be created? I guess if you never plan to go beyond a specific point it doesn't matter, and extends the life apparently. Interesting.

The other difference between AO-27 and SO-50 and the Fox birds is that the Fox birds had a continuous carrier once the transponder was activated, for up to a minute even without use, IIRC. So that could cause a deeper depth of discharge.

I also would love to know more about SO-50. It seems like a mystery. It just works, it never is commanded into a different mode, and it's been going for almost 18 years apparently. Amazing. When that one goes, it will be even more disappointing.

Again, thank you very much Jerry and Steve for your informative posts.

73, John Brier KG4AKV