💬 Re: Boat Electrics. Wiring Diagram
"yes I could have paralleled up the batteries but"
If I'm not very much mistaken, or the diagram is mislabelled, that is exactly what you have done Hillro!
Both positives are connected via the fuses and both negatives via your negative rail.
If you MUST do that then you have to make sure that both batteries are identical.
That doesn't mean just the lables!
It means that they both must have the same actual voltage and state of charge.
Otherwise the stronger will start to try and charge up the weakest, which can lead to some excessive current and associated heating 💥🔥😭
To prevent that Schottky power diodes should be inserted into the + leads of both batteries.
A simple and neat way to do that, if you don't want to do the soldering yourself, is the Parallel Connection Board from Action Electronics (Component Shop).
And yes, F3 and F4 are back to front😮
Cheers, Doug 😎