There have been a number questions about batteries and their use.  Much of the information I have been posting here comes from a web site called Battery University.  This is an extensive site with all kinds of information, more than you ever wanted.  However, it does contain a lot of basic information that can help you make decisions about your needs.  I have found it quite useful if you take time to navigate through all their pages.  Best, however, is that it is not full of ads or pop ups.

The home page is:

http://batteryuniversity.com/  

Information about lead acid batteries and links to all the information on lead acid (life span, discharge rates, charging rates, etc.) is at:

http://batteryuniversity.com/learn/article/lead_based_batteries

Tom