We were planning to rewire the boat completely during this fall, but as it turned out, it couldn't wait. When I started the engine before heading out for a one week sail, the battery warning light came up. According to the manual the light might indicate incorrect voltage from the generator. When I checked it with a multi-meter, it was very high indeed, well over 15V, so it was overcharging the batteries, which carries the risk of gas leakage or explosion. So we decided to investigate it further and delay our departure for vacation. After disconnecting the house bank, the alternator output normalized, so we concluded that the old battery probably had dead cells so the alternator was trying really hard to charge it. But to connect the new batteries properly (which we placed in a new location) we had to rewire almost everything. The electrical refit project has been started.
But first, here are some before pictures (be prepared for the horrors):
One interesting thing is that there was no negative busbar on the boat and all negative wires were lead to the main switch, which was breaking the negative side of the circuit. This resulted in such horrible solutions as screwing one wire into the other or using terminal strips for connecting multiple negative wires. So we decided to replace everything step-by-step and improve on the situation in every possible way.
New 12V systemFortunately I already made a wiring diagram of the desired system, we just had to implement it. I marked the terminal screw and wire sizes on it too which helped a lot during the installation work.
(updated with isolation switches and solar panels in September of 2020)
Read Part 2