Re: Jeanneau Attalia
I have mine in the same location - only that the starting battery is in the same compartment. My wires are much more messy than yours. They are, however, all linked to the switch board panel next to the navigation table - with proper fuses (push buttons) The few exceptions (e.g. heater) have separate fuses. My charger is in the cockpit locker.
You are right that the batteries should be better fixed - one terrible story from the Fastnet race in 1979 was a battery flying through the main cabin. Mine are fixed with a wooden board across the batteries and fixed to wooden boards on both sides of the compartment, installed for this purpose. Good idea with the boxes to collect possible spills of acid.
Sailing in Denmark