Help please! Wiring Setup

[CTsalt12]

Okay so I bought a boat that seems to have some fishy wiring, or some shoddy work done to it.  Not sure what works except for the starter, so I'm in a rather precarious spot.

It's a two battery setup I believe, as it came with two, and it has washdown pump, stereo, Sounder, bilge of course, and nav lights, and supposedly 175's have live wells, no idea where this is, as the cooler in front of console has no hole for pump to come through. It would have to run on two batteries with all this, right?

--BUT--

There is only one positive wire coming from the battery switch, and more than one negative wire.  However, there is another positive wire coming from below deck....?

Could someone please explain this? I have looked at multiple electronics diagram, and I have gone through 12 Volt bible to no avail.

[Capt. Bob]

Look this is Seabob's meat and he'll stumble along shortly but I gotta ask anyway..

Is the switch a 3 position battery switch with positions 1, 2, BOTH and OFF?

If so, will the starter crank in position 1 or 2 or BOTH?

Just curious.

[CTsalt12]

It's a switch with 2 battery setup, 1/2/ALL.   To be honest I'm not sure if it will crank on both.  P/O cranked it for me when I bought it, and my batt's need a charge at the moment I assume, cause I couldn't get it to beep and I tried all combinations

[Keith Knecht]

SeaBob is the expert here but I'll take a quick stab at it for now till he chimes in.  The positive wire coming from under the deck should go to the back of the switch on the terminal marked C or Com.  A positive wire from position #1 on the switch should go to battery # 1 Positive.  The negaitive wire coming from under the deck should go to the negative terminal of battery #1.  A positive wire from position #2 on the batter switch should go to the positive on battery #2.  A negative jumper wire should go from the negative of battery #1 to the negative of battery #2. In this configuration the switch in position #1 will run off battery #1 and the switch in position #2 will run battery #2.  In position all or both, depending on the type of switch you have, both batteries will be tied together.

[GoneFission]

Post some pics of the wiring and pics and we can see what you've got.

[seabob4]

In the meantime, here is a typical wiring set-up for a single engine boat running 2 batteries.  Ignore the ACR and the 40A breaker...



As Kieth stated, the idea behind a dual battery switch is that you can both combine and isolate the batteries for starting and house loads.  Not seeing what's actually going on with your wiring, keep this in mind.  The only items that should be wired "constant hot" are your bilge pump float switch and your stereo memory, if you have a stereo.  EVERYTHING else should be wired to receive power from the common post, or "switched hot".  Constant hot means even with the battery switch in the off position, those items will still be powered.  Switched hot means when you turn the batt switch off, no power is present...

Like CJ said...

[CTsalt12]

The legend speaks...

Thanks a lot for the diagram, that is the most clear and easy to read one I've seen!  However, I've decided this is a job way out of my capabilities, and I'm having my boat guy re-wire everything, as it's completely disorganized and jerry rigged at the moment.

Some previous owner even installed non waterproof switches....Needless to say everything's a mess but I will post pictures of the final product.