Join Date: Mar 2006
Location: Fort Lauderdale
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If you can only fit 2 batteries, then I would go with a Bank of the SCS200 (12v) in parallel.
Here is the reason. If you're using this as your one and only bank, and a single cell goes bad (which ruins the battery that the cell is in), then in your first setup (6v in series), you will lose the *ENTIRE* battery bank as most electronics require 12v.
In a 2 x 12v battery in parallel setup (your second scenario) if you lose a battery due to a bad cell, at least you have 1 additional battery that is capable of putting out 12v allowing you to limp home. Sure your capacity is diminished, but this is an emergency situation...and a prudent sailor tries to prepare.
Ideally, in a long term cruising scenario, I would have 4 x 6v batteries wired in series/parallel. This would give me 2 x 12 banks totalling ~400 amp hours. This is a lot of weight and the cabling and charging equipment can be expensive and require upgrades, as well as the ongoing battery maintenance....however I would have the most peace of mind with that setup that my bank(s) can provide the capacity and redundancy I seek.
Last edited by night0wl; 08-30-2011 at 02:10 PM.