The 12volt Side of Life Part 2 (http://www.marxrv.com/12volt/12volta.htm)
Another excellent source is reading Handy Bob's Blog (https://handybobsolar.wordpress.com/faqs-please-read-this-first/). Even if you aren't looking to go solar, he has excellent information regarding batteries, charging, and capacities.
There is some good info there but it is a little dated. It looks like it was designed in 1989 but is dated Sept 2000.
see ya
ken
Handy Bob has been updating information and the last updates are 2016.