Help with Wiring. 3 lost negatives

S

Solesurfer

New member
Hello everybody,
I currently in the process of swapping out my fuel tank on my CD25. I figured I would clean the bilge the best i could and remove the batteries from any water that might splash.
In my haste I didn't properly note all the wires(bone head move) and now I found I have 3 negative cables that aren't connected. I traced all the wires and produced this diagram.

wflC0Sr.jpg


I don't have a solid understanding as to what all my switches do, but i'm trying to figure it out. Also my battery charger isn't working as the problem is probably those loose wires and I'm worried my batteries will go bad.
Can anyone point me in the right direction?

Thank you,
Tom
 
From your diagram, it appears that no negatives go back to the "House" negative bus bar. These would include the negative to the console, the battery chargers, and the negatives to any pumps (including bulge, macerator and wash down.).

This is why I love to have a long wire with alligator clips on both ends. I can use that temporary wire to be sure where circuits go.

Check each system, pump, light, charger etc (including stove), and see what work and what don't. That will give you an idea where to start. That the battery charger is not working --is a clue that its ground (may require a separate to each battery?). is not attached.

Also a great time to label each wire. (both positive and negative)

Good luck and keep us in the loop.
 
I haven't really done any analysis of your diagram or situation, but as a general rule all negatives go to some sort of negative bus or to a battery negative terminal.

Frankly, your diagram is incomplete at least to the point that the 2 batteries you have connected in parallel do not have their combined negative going anywhere. If I assume that those 2 batteries are for the house, and the single battery is your start battery, then it is unlikely that you can go wrong putting those 3 wires on the negative bus. All 3 are likely house circuits since most start batteries don't use buses, but rather go straight to the engines from the battery with large cables. Start batteries don't often power any other circuits. The exception to all this is the charger(s). They often go straight to battery posts (+ and -) with separate circuits for each battery bank (house and start). You'll need to verify that those 3 negatives are not from the charger(s).

Later edit: I had not yet seen thataway's post when I wrote mine above. Any conflicts are accidental.
 
thataway,

I'm curious how to use the long wire with alligator clips to verify where wires go. That would be a very handy "tool in the toolbox".

P.S. I do understand how to use such a long wire to determine whether a load that is not working has a bad wire, but I don't know how to use the long wire to determine where an unknown wire goes.
 
Is it possible to track back wires to dash?

You could use a circuit wire tracer that consists of three parts: transmitter, receiver and probe. The transmitter is connected to one end of the circuit, such as an electrical outlet. It transmits a signal that travels along the wire it is connected to. The receiver is used to detect the signal being transmitted on the electrical circuit.

https://megadepot.com/resource/why-and- ... it-tracers

You need to disconnect all battery cables and might be flipping switches on and off.

I am not sure the best approach except call a bot or auto electrician
 
smckean (Tosca)":2w3jxkvy said:
thataway,

I'm curious how to use the long wire with alligator clips to verify where wires go. That would be a very handy "tool in the toolbox".

P.S. I do understand how to use such a long wire to determine whether a load that is not working has a bad wire, but I don't know how to use the long wire to determine where an unknown wire goes.
Click to expand...

The first thing I do is to be sure that these black wires are negative--occasionally someone has used black wires, with some red tape at the ends, for a positive circuit...so I put one clip on the end of that black wire, the other clip on the pos. of the volt meter, set on DC 20 volts, taking the neg. lead to the battery terminal. No voltage, would verify that this is not 'hot 12V" and safe to hook up to the terminal. Then, I would use the wire with the clips to connect temporarily to the negative terminal--and see what appliance or system then came on.

To specifically check where the wire is going--make the best guess, jump from the battery to that point--and see if it energizes the circuit. It may take trial and error.

I also use it to temporarily get power supply to any appliance at a distance. Lets say I don't have 12 volts to the console--I am not sure if it is the battery switch, or a breaker in line, or a swage which has pulled out. I connect the one end of the wire to the Pos. bus bar under the console, and then start with the battery, the output of the switch, the output of the breaker to see where the interruption is. There have been cases when I needed temporary power, until I got into calmer water, or daylight and could trouble shoot where the problem was. For example I was offshore, at night, and the GPS quit. I used the wire to jump directly to the GPS circuit--and in the Morning, sorted out why that circuit was not working.

Brent I do have several types of signal tracers, I have used with my ham radio or with household circuits. They are battery operated and self contained--several will have difference resistances at the end point--and thus I can ID by the resistance found, others use a beep signal to show an intact circuit. Some put a carrier frequency on the wire, to be ID. But I think in this case, simple will work.
 
I thought I was the only one that took the wires off the battery and forgot where they go :)
Looking at your drawing. I would say the negative from the port engine needs to go to Negative bus bar. The negative from the starboard engine also needs to also go the the negative bus bar.
The negative that you are showing coming FROM the negative bus bar needs to go to one of the negatives of the two batteries that are paralleled.
Like Bob said some times black wires are really positive but in your case I think it pretty safe to say that they are negative because you gotta have a negative for each engine and the negative bus bar has to be connected to the battery negative. Now if you also took the wires off the different bus bars then the more intense tracing is required to get them back on the correct bus.

roger
 
Thanks, Bob

Using your recommendations, leave the power on then all panel switches on ? If not on panel then investigate further
 
Definitely there needs to be one cable from the two parallel batteries to the ground bus-(and I suspect there is a negative to the outboard).

The question is what battery charger do you have? Is there one ground for the entire charger, or one ground for each circuit? That can be important.

I have both a volt meter which will measure the current on one side of a circuit (that is by clamping over the wire (not on the wire). I also have an ammeter which uses a negative shunt, and will measure the current being used by a device, or delivered by a charger. This could be important to determine if the battery charger is properly working. The easy way, is to just put the voltmeter on the battery. If it is over 13 volts, there is a very good chance that the battery charger is working. (It may be up to 14.4 volts).

As Solesurfer notes it is very important to:
1 take photos of wiring when you detach it.
2. Put labels on the wire--if you have to cut--put "a" on each end, "b" on the next wire etc.
3. make a wiring diagram. before you disassemble the circuits.
 
thataway":2snhbma2 said:
To specifically check where the wire is going--make the best guess, jump from the battery to that point--and see if it energizes the circuit. It may take trial and error.
Click to expand...

Too bad. I was hoping there was some dependable and quick way to trace a wire that goes to an unknown location other than by buying a circuit wire tracer (rather expensive) that BrentB mentions above.
 
You might check rental shops for them.

Might was cheap and now non working


Post an update

Also neat to know how problems are resolved
 
Thanks for all your responses. I finally got around to working on it more and I think I found where those wires went.

ylZw0dL.jpg


So port engine negative wire and the other negative bus go to my house bank batteries on the right. The starboard negative goes to the battery on the left. Engines turn over and pivot up/down, while the battery charger shows the correct charging light.
I understand the switch to turn on the 1 and 2 batteries, but why are there two switches on the left? Could it be that if the starting battery doesn't work it can rely on the house batteries to start?
 
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