I have no idea why not to tie a line of 12V deep cycle batteries together in a parallel series? I have had 5-7 of the group 31 12V wet cell batteries paralleled together in our 5th wheels since 1993 to run the 2000 to 2500 inverters I installed in the 2 5th wheels. 2 more batteries are in the back of the pickup tied to gether always. ALL batteries in my systems are the same size!
My last 2 trucks have had dual alternators with #2 gauge fine strand welder cables in their split plastic wire protector cable tied to the upper inside of the truck's frame. 1+ and 1- going back to the bed batteries with an 80 amp slow blow marine fuse on each end of the cable and an 80 amp slide switch under the hood to disable the cables.
Battery life of all has been 5-7 years before I replace them and they still weren't going bad but I don't want to be in some remote place and have a battery failure. I use the old batteries in our boats etc and a couple are over 10 years old now an still going strong. Not taking a chance of either can't get a replacement or have to pay about double for who knows how old the new battery/batteries actually are when boondocking in the wilderness. Murphy's law!
In the 5th wheel, one battery on each side in the OEM battery compartments and 3-5 in the front storage area in a covered mounted box vented out thru the floor with either 3/4" ID or 1" ID PVC white water plumbing glued together. Installed a 500 amp marine barrel switch under the overhang with the #2 gauge from the batteries to disable them. Then there's 2 of the same cables coming out of the back of the pin box that go to the junction block's 3/8" brass wingnutted studs just behind the bed batteries that also connect the alternators and the bed batteries. When driving even a short distance or running the diesel engine and short time all 7-9 batteries are quickly recharged and at full charge long before we get to where we are going. 1575 - 1785 minutes at 23 amp draw max! Never have drawn them down to even 50% yet. Also charges the 2 truck's batteries from the alternators of course.
For our TC's, 2 in the bed and one in the TC paralleled together for the 1500 watt inverter inside. 675 minutes at 23 amp draw max!
My various systems have worked perfect and the batteries last so long. Of course, I don't use sealed batteries or gel batteries because I keep the water level well above the plates on all batteries. I also recondition all the batteries once a year individually with my 2 higher grade battery chargers. One is a 25 amp and one is a 40 amp auto with digital readouts. Takes 24 hours each for reconditioning which cleans all the plates in the batteries and brings them back to 100%. In all those years, only 2 batteries have ever failed (shorted) after their term in the RV's. Still got $10 each exchange for them when buying new ones and back in 1993 they only cost me less than $60 new.
Why would it be any different for solar as you could never over-charge a large bank with solar trickle type charging and there's an auto cutoff anyway when fully charged on the systems we looked at? To me, solar is a very expensive way to go and their service life is not long enough. Be sure to check that out as it may be in fine print or not even stated! 2 of our camping friends found out the hard way and don't use solar anymore!
Just have to think outside the box and use what long proven not be swayed by gimicks or expensive rube goldbergs that may or may not do what you want!
