Hi,
I must admit to electrikery not being my strongest subject
Recently I replaced the House battery with a larger one (85 to 105ah)
I carefully photographed all the wires, tied the common ones together, and then connected the new battery exactly the same way as the old one.
Only trouble now is that the new one won't charge as it did in the old installation.
I can get the new house battery to charge if I connect it in parallel with the starter battery (jump lead to +ve posts)
I have two independent battery switches and can't link in parallel in case of an emergency (I have jump cables