In regards to batteries of any type, it really pays to do a little research.
The store bought batteries you get for your flashlight etc. etc. have a limited lifespan and this is diminished (admittedly by a very small amount) in hotter weather. Store them in a cold place and they'll last just that little bit longer.
In regards to using and recharging car batteries, you want to read up about the benefits and penalties of using serial versus parallel battery connections for your specific energy requirements.
I've found
this site (Battery University) to be helpful in regard to both things mentioned above.
Specifically: -
How to store batteries
Battery configurations
What causes car batteries to fail
And for those who want to get a bit more involved in energy requirements,
this page could be useful for T2k