6v batteries typically discharge slower and recharge faster over a 12v battery. They tend to be easier to maintain because of this.
You must have at least two 6v batteries connected in series so that they provide 12v. Then to do the equivalent of two 12v batteries in parallel, you must get another two 6v batteries and connect them in series (to make 12v) and then connect these two sets of dual 6v batteries in parallel.
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