We bought a boat that has a main engine and two side engines. Main engine is what is usually used. Each motor has a 12V and a 24V alternator. There is a 24V AGM leisure battery bank and two isolated starter batteries. Through the isolators each motor can charge all of those. There are also two solar panels with one mppt for 12V and one mppt for 24V. Everything is about 20 years old and there are some electrical problems. Most acute one being that one of the alternators malfunctioned and fried one of the isolators.
To me it seems that it would best to rebuild the whole system. Starter batteries are old so I'm going to replace them. I could go for one starter battery per engine and DC-DC chargers in between the batteries. How does that sound?
How should I handle the 24V battery bank charging?