A Really Strange Wiring Problem that I need Advise on....

[blairv70]

So up early this morning armed with some advise - thanks everyone. Yes all grounds where wired to the hull:

Old Switch.jpg

So I have rewired as follows - does this look correct?

Rewire.jpg

Now all ground wires are to the negative terminal on the house battery and the engine, bilge and accesories positives are on the common rail of the battery switch.

Will wait to see if anyone tells me different before I put it all back togather

Cheers

Blair

[patrol50]

looks ok to me mate but i an no expert and very similar to mine after i changed it in the quintrex that was earhed to the alloy hull also if you want to you can run a biggish positive lead and a separte neg lead from there up to buss bars / fuses and power what ever from there i run my lowrance sounders like that on a separate feed to keep it isolated from everything else - just remember you will almost certainly have the OB earthed to the boat not much you can do about that as far as i am aware but one of the 12 v gurus may have a solution for that

cheer rob

[juggernaut]

just remember you will almost certainly have the OB earthed to the boat not much you can do about that as far as i am aware but one of the 12 v gurus may have a solution for that

cheer rob

Couldn't you just rewire the O/B neg to the neg of the battery thus removing it from the hull?

[juggernaut]

Mate, you mind posting the link where you got yours from..looks spik..

Here's a link to a bloke in WA I've used in the past.

http://www.ebay.com.au/itm/Blue-Sea-...item3f2298b77f

[whaler]

Looks ok. Only other thing to check is that the size of the negative for any circuit must match the size of the positive for that same circuit as, of course, the returning current is the same as the feed. It looks like you have that covered in the photo. Subcircuits can come down in +ve and -ve size as appropriate but ensure that they are protected by fuses sizes to the cable rating and locate them as close as possible to the busbar just like the main feed fuse should be as close as possible to the battery.

[thelump]

Just something else to think about. I don't know your dash layout but my main bus bars are away from where my switch panel is so I ran a second negative bus bar from the one under the dash to directly below the rear of the switch panel. This just made wiring things to the switch panel neater and easier as I didn't need to split the positive and negative and run them in different directions.

[blairv70]

Just something else to think about. I don't know your dash layout but my main bus bars are away from where my switch panel is so I ran a second negative bus bar from the one under the dash to directly below the rear of the switch panel. This just made wiring things to the switch panel neater and easier as I didn't need to split the positive and negative and run them in different directions.

Lump I have done pretty much the same thing - a seperate negative bus bar near the switches. The distance is not that far but it will help with keeping things neat and tidy. Picture of the nearly finished project attached

[patrol50]

Couldn't you just rewire the O/B neg to the neg of the battery thus removing it from the hull?

i believe its a bit more complicated than that on an alloy hull as have to isolate all metal parts on the OB from any possible contact in any way with the alloy hull i.e. via isolating the OB mount thru bolts for instance etc etc - it can probably be done but is it really worth the effort not too sure about that

cheers rob

[Fed]

Use your motor accessories power for all the motor gauges plus fuel gauge and voltmeter if you have one.

Run a fused positive from the 'COM' switch terminal to your dash.
Run a negative from one of the NEGATIVE battery terminals to your dash.
Use these 2 wires to power everything else via whatever switch/fuse board you put in.
(If I find a diagram that covers it all in one go I'll post it for you)

Make sure the only negative going to the hull is via the motor to transom bolts.

You seem to have too many wires connected to your battery.

[blairv70]

Use your motor accessories power for all the motor gauges plus fuel gauge and voltmeter if you have one.

Run a fused positive from the 'COM' switch terminal to your dash.
Run a negative from one of the NEGATIVE battery terminals to your dash.
Use these 2 wires to power everything else via whatever switch/fuse board you put in.
(If I find a diagram that covers it all in one go I'll post it for you)

Make sure the only negative going to the hull is via the motor to transom bolts.

You seem to have too many wires connected to your battery.

Fed

Yes I agree I seem to have too many negative cables - There were three originally wired to the hull above the battery switch - two thick cables and one thin cable which is for the accessories.

I have now moved all of these to the house battery - what would the other two negative be? They are pretty thick - probably around 10mm of so - trouble is it is hard to get into the transom fully so I can only speculate what they are.

I am still having the issue that when I hook everything up (sounder, vhf etc) I still get nothing - the voltage drops as soon as i turn anything on. I ran a cable directly from the accessory bus to the house battery and everything works fine - it just seems that the existing cable from the batteries to the bus has some sort of issue causing a voltage drop.

I am thinking of bypassing the existing cable all together and installing a new cable.

Any idea what the other two ground (negative wires) could be? Is there a seperate one for tilt and trim perhaps?

Thanks

Blair

[juggernaut]

i believe its a bit more complicated than that on an alloy hull as have to isolate all metal parts on the OB from any possible contact in any way with the alloy hull i.e. via isolating the OB mount thru bolts for instance etc etc - it can probably be done but is it really worth the effort not too sure about that

cheers rob

Sorry I misinterpreted your previous post - I thought you were only referring to the o/b neg lead that Quintrex bolts to the hull.

Agree re outboard mounting.

[blairv70]

Wiring Diagram.jpg
Here is a full diagram of my wiring setup

[juggernaut]

Fed

Yes I agree I seem to have too many negative cables - There were three originally wired to the hull above the battery switch - two thick cables and one thin cable which is for the accessories.

I have now moved all of these to the house battery - what would the other two negative be? They are pretty thick - probably around 10mm of so - trouble is it is hard to get into the transom fully so I can only speculate what they are.

Blair

If its a Quintrex if found that - one thick neg was from the outboard, one thick neg from the battery and the other thin from the accessories.

When I rewired mine I installed a neg bus bar down the back of the boat and placed all the negs on the bus bar to alleviate stacking them on the battery post. I also run a dedicated neg off the bus bar to the bilge pump.

[Fed]

Very old Mercurys used to run extra wires for the T&T but now days they all run from the main motor wiring.
What motor do you have?

You may fiddle around & get it working but it could still be very wrong and cause you big problems further down the track, what area do you live in?

[blairv70]

Very old Mercurys used to run extra wires for the T&T but now days they all run from the main motor wiring.
What motor do you have?

You may fiddle around & get it working but it could still be very wrong and cause you big problems further down the track, what area do you live in?

Hi Fed it is a 2006 Mercury Optimax 2 Stroke so not that old. Looking at the Manual it would suggest only two wires from the engine (pos and neg) and the wiring for the instrumentation cluster.

I live in Carindale on the Southside