By the way, One if the issues with the "How many batteries" or "one or two, or 6/12 or whatever battery discussions....
Usually when we talk about six volt we are talking GC-2, six volt, 230 amp hours, true Deep cycle
But when it comes to 12 volts, I have some here just a few amp hours (AGM's) that I can easily hold in one hand... I have others in the 70-80 amp hour range I need two hands to wrestle in and out.. and I have some group 29s, just over 100 amp hours... An 8-D is around 250 amp hours. and Ive used 12 volt DEEP CYCLE flooded wet cells that were so heavy that they strapped it on a pallet, and loaded it on the trailer with the aid of a fork lift.
By the way. an identical battery powered the fork lift
That puppy tipped the scales at over 1,000 pounds.
So, it is very important to tell us WHAT 12 volt battery.