Four 6V vs two 12 V house batteries
This is directly from a battery manufacturer as to the difference between similarly rated 12V and 6V deep cycle batteries for RV applications and why 6V has an advantage. Take it for what it’s worth.
Advantages and Disadvantages of using two 12 volt batteries connected in parallel or two 6 volt batteries connected in series:
It would appear that there is no significant difference in capacity and voltage between these two examples. But this really is not the case. The plates designed for the T-105 use the same active material and alloy of the group 27 deep cycle batteries but both the T-105 negative and positive plates are 60% thicker than those found in the deep cycle 27 group sizes. The significance of this is that these 6 Volt batteries should have a longer lifespan than the two deep cycle 27 group sizes, if properly cared for. While the capacities are similar (220 versus 225 Amp Hrs.), battery longevity favors the two 6 Volt batteries. Why? Because a major cause of deep cycle battery failure is the shedding of active material from the battery plates.
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