More juice, lasts longer. Stuff runs on 12V no matter how many batteries you have. 1, 2, 200, 1,000 whatever.
I have FOUR 6V batteries, which just makes 'em last longer than two 12's. Just connect 1 and 2 in series to make 12V and 3 and 4 in series to make 12V and connect the 1/2 to the 3/4 in Parallel as if it were just two 12V's.
Simple as mud.
"Next to prayer, fishing is the most personal relationship of man"Calvin Coolidge
"American by Birth, Southern by the Grace of God"Lewis Grizzard
2016 GMC Denali 3500Dually--2017 CC 36CKTS