In the ten years I've owned my boat, I've never had much need to go poking around the cranking battery since I removed the electronics to a separate system. But the boat's been in to the shop several times since then to add trim tabs, jack plates, electric downriggers, and on an on. Apparently, none of the shops ever thought it might be a good idea to stop adding stuff to the house battery studs and create a proper marine electrical system off the cranking battery...
So there is no more ignorance is bliss with this mess. I fish in some really remote locations prone to rough water, and this mess is becoming a potential safety risk. It's time to pull the battery out, figure out what wires are for what, and create a properly-powered fuse panel similar to what I did for the electronics system. Here's what I've come up with so far...
1) I'll need to add up the all the amp draws for everything to make sure another 125 amp fuse panel will be adequate. The plan is to then run the proper gauge of wire (as indicated by the attached chart), with a properly-sized circuit breaker off the positive stud of the battery. Energizing the fuse panel will be controlled by a battery switch.
2) I'm not sure if the main outboard is normally controlled by the battery switch, or if it should remain directly connected to the battery.
3) I've heard some people leave the outboard's tilt/trim wired directly to the battery so it can be operated at the boat launch without having to climb in the boat to turn the battery switch on. Is this viable? Are there even separate wires for this or is part of the main power for the outboard?
4) While I am thinking about it, is there anything that should bypass the battery switch and be wired directly to the cranking battery?
5) Any recommendations on how to determine what each wire is for without tracing them all the way back to their origin? That looks like it could be difficult for some of them. Just pairing the positive and negative leads is going to take a bit.
6) I'm not sure where I'll mount the fuse panel or battery switch as I have a new MK230PC charger to replace the MK106 currently tucked under the livewell. I think it's going to take most of the space between the battery and the current MK106.