On Fri, 17 Apr 2009 21:10:59 -0400, "Flying Pig"
wrote:

What is the recommended, real-world cycle? That is, how low do you
take your flooded batteries on a regular basis? Related, is there a
readily available source for information on the numbers of cycles to a
given percentage of discharge in a battery life span? I.e., 500
cycles to 50% and back to 100% but only 100 cycles to 20% and up to
75%, or the like (recognizing that these numbers have no relation to
any battery made)?

There is some pretty good information in this deep cycle battery FAQ:

http://www.windsun.com/Batteries/Battery_FAQ.htm

50% depth-of-discharge is a good working average with 80% an absolute
maximum. Our house bank consists of 4 Trojan golf cart batteries and
we get about 3 years out of them adhering closely to those guidelines.

I have seen figures quoted that regular cycling to 80% DOD will cut
battery life in half.