Yes, that is correct. That is the way batteries are connected in RV's. They connect multiple 6v batteries together in a combination of series and parallel connections to get a battery bank that puts out 12v. There's multiple ways to do it. Here's a picture of another way that would work. In the picture below, they are using 6v batteries to end up with 12v. If you do the same with 12v batteries, you'll get 24v.

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