The idea behind the install
(Comment: We have upgraded Horizon to Lithium technology. So this is not how Horizon is equipped today. The information is still valid though)
I did a lot of research on how to make a balanced battery bank as big as we have on Horizon.
The set-up is basically two "totally balanced" 4-battery banks that are installed in parallel, which make the total bank absolutely (100%) balanced. What that means is that each individual battery will have the same potential (voltage) regardless of the amperage going in or out of the house bank. Which will improve life of each battery. This is accomplished by having each individual battery seeing exactly the same number of connections, and seeing exactly the same length cabling to the terminal. This is why it looks a little messy, but make perfect sense from an electrical standpoint.
I bought all cables pre-made (Amazon), instead of taking the time and effort building them myself. I also bought some new longer bolts for the firefly-batteries, where I had multiple connections on the same terminal.
The set-up has worked very well for us so far. 928 Ah capacity is great. We were at anchor close to New York City, and it was close to 90 degrees at night. So we were running the AC in the forward cabin for 12 hours straight (8pm to 8am), and still had 50% SOC (State Of Charge) in the morning, pretty impressive.