Battery cable break

After much searching I have come to find out that the cable from my #1 battery to the DC panel has a break somewhere between the two ends.

Background: Have two start batteries (one for each engine), off each battery there is one cable to the starter, one to the DC panel as shown on boat builders diagrams.

PO added house battery and heart charger/inverter which is connected to the common lug of the 1/all/2/off switch on the dc panel, which has its own switch to control the house battery.

While trying to figure out what had been done by the PO(s) some weird things kept happening and I finally traced it down to the cable from the #1 battery to the switch has no power. Got some small wire and connected both ends and put a meter on it and there is no continuity.

Right now I have the battery end disconnected since I have no idea where the break is and I would rather not have a live end somewhere.

I am guessing this is about a six to seven foot long cable that snakes through some very close quarters and will be a bitch to replace. And of course no readily obvious problems with the parts I can see.

SO now the questions:
Anyone have something similar happen?
Any ideas on how to find the break?
Any shortcuts to pulling a new wire?
Should I ignore the whole thing since I really don't need the connection because of the additional house battery?

Well, I think that it is very unlikely that a cable to your DC panel actually broke. More likely it goes to some terminal block and the connection is loose.


But if it really did break, can't you disconnect both ends, securely connect a new cable to the old one (use an appropriate crimp connector and wrap with tape to make it strong) and use the old one to pull the replacement through the tight spot.


David

Had not thought about a terminal block. One is not shown on the plans, I will have to look for one.

Unfortunately the old (current (currentless)) cable runs in some cable trays and bundles that are pretty tight. Even when I cut the tie wraps nothing moved. And I am not skinny or young enough to get into the spaces available where the old cable is.

Please clarify ..
You ran a small wire from a positive terminal to the switch terminal and showed no continuity ?????? what does that have to do with your battery cable ?

Whether or not your"small" wire has or does not have continuity tells you nothing about the battery cable. Have I misunderstood what you are saying ?

Have you considered that there should be a fuse or circuit breaker close to the battery connection and it might be blown or tripped?

I connected a wire to one end of the cable, took the other end of the "small" wire to the other end and checked for continuity, which there was none. Thus my conclusion that there is a break somewhere. Used a "small" wire because my meters leads counld not reach both ends of the battery cable.

As to a fuse, have not seen one, plans do not show one, and the first two or more feet of the cable does not have a fuse. But that is something to investigate. Thanks.

Greetings,
Mr. ww. One thing you might try in conjunction with your "small" wire test, as a last resort, is connect the "small" wires as before and starting at one end, push a small straight pin through the wire insulation to contact the inner copper wire. By moving the straight pin along the wire and testing with your VOM you should be able to isolate the stretch where there may be a break. I'm with the other guys though and think it unlikely that a battery cable is actually broken.

As WesK mentioned it is probably a fuse.

I like RTF's idea (mostly); I don't really like the idea of punching small holes through insulation and risking water intrusion. Are there not voltage sensors, like for testing Christmas light strings, that would show you whether something's hot?

It would seem to me that failure is more likely in the terminals than in the length of cable. Is the insulation 'swollen' at the battery end? My car experience was that corrosion from battery acid could corrode the wire within the insulation.

Do you know that the battery terminal post is actually still connected to the internals of the battery? I've seen that failure, too.

I rather doubt you could pull a new cable through the bundle of existing wires unless you freed all of the bundling, and maybe not even then if the bends are even a little bit tight. ( I had to replace one of the cables in my 83 Volvo Turbo automobile - coasted to a halt on the Schuykilll Expy; the battery and cable was SMOKING hot! - and ended up splicing the new to the old because of how it was run next to the engine block; I simply replaced the burned couple of feet.) OTOH, you can chop the old cable off at each end of the bundling and run the new one as adjacent as possible; your next owner/surveyor won't like the look of it, though.

If the cable is actually broken, it may well mean that the insulation was pinched and it shorted to something big, like the engine block, and burned through (my cables are as yet not fused and are run next to the engine mounts). Think how lucky you are, so far, and make sure that's not the case!

Not sure of the age of the boat....

If the boat is older it may not look like the builder diagrams any longer.
If the boat is older it likely doesn't have the positive battery cables fused near the batteries as is standard now.
If there is a break in the cable it would take something significant to cause that. Since the cable bundles are as tight as you describe, I would worry about the other cables in the bundle.

Greetings,
Mr. DH. " I don't really like the idea of punching small holes through insulation and risking water intrusion." Valid point and I agree but qualified with "as a last resort".

Every man to his trade.. call a marine electrician.

There are fuses that go between the wire end eye or lug and the terminal they attach to whether a battery switch or buss bar/terminal strip.

If not noted they can be a major PIA to find. Helping a fellow because his windlass would not work and after two hours found one of these. No notes.
They are a good way to protect wiring where there is not room to install a more typical fuse and holder especially in retrofits. I use them for that reason.
BUT, they need to be labelled or noted somehow.

www.bluesea.com/products/category/16/Fuse_Blocks?Fuse_Type=Terminal[/url]

https://www.bluesea.com/products/category/16/Fuse_Blocks?Fuse_Type=Terminal



Look at the MRBF type fuse. A little square block about 7/8" square by 1/2 thick.

EDIT:

Should have said that maybe you have one of these block fuses at the V source and it has blown. Take a good , hard look for one. The only way is to test it if you have one

Lots of really good ideas above, on the off chance you have to run a new cable through a contorted space....
Find the most flexible, multi stranded ABYC rated cable you can. Really good welding wire is supple and VERY flexible.
Pull the old out, with a suitably strong string attached. You do not need the big bump of two big cables taped together being pulled through a tight space. Pull the new wire through with the string. Good luck.

Hire someone young, dumb and full of beans to run the cable under your supervision.
I have seen corrosion travel up a cable several feet. Often when trying to figure out why a good alternator isn't charging right.

I have also seen that corrosion run surprising distances. Heaps of good advice on this thread.

Yes - Possible blown fuse (most likely), possible corrosion, possible break.

The other possibility is the continuity check was done on the end of 2 different cables. Don't bet your boat on the plans being still correct.

I've had two battery cables fail on heavy equipment in the last few years and on both occasions it was the factory soldered cable ends that failed.

Crimped ends are the only option in my opinion.

Conall

X2 - corrosion inside the lovely oem red plastic/rubber coating. On every single 6 year old Prevost in the major carrier's fleet.

As is usual, one of the old mechanics, frustrated with the recurring electronic issues, carved into the cable end with a knife, and found it a mass of green dust void.

I am no fan of piercing wires with probes, especially in a marine environment. Carve into the cable ends first, if you pierce, choose some permanent type goop of your choice to seal the jacket.

RB

I would disconnect one end of a wire and check continuity. Then I would feel and pull on the wire and see if the copper is broken inside. Then I would replace the wire or repair the break.
You can also clean copper wire corrosion by soaking in phosphoric acid (great cleaner) or vinegar. Then rinse and sometimes suck the wire with a vacuum pump, etc.. don't ask... I usually crimp, solder, heat shrink all my repairs and connections. Been doing it for decades with no problems.

I have only had a few wires on the old 1970 boat that failed. Oddly the soft SO jacketed rubber wire they used on the bilge pumps has had the insulation rotting and cracking.
None of the other styles of wire they used has had any trouble at all.

And most of the bonding wires they used was solid copper 10 gauge, and you would think that might be a problem lying in bilge water for 45 years, but it was not. Maybe because water cant easily wick up between the insulation and the copper. Just saying!

I don't pierce wires except in a case of extreme frustration. Did that on an Isuzu PCM wiring harness trying to figure out why the TPS was not sending signals to the PCM. Turned out finally was the multi wire plug end, loose metal socket on the signal wire at the PCM. It was very intermittent and difficult to figure out. I soldered around the socket plug those 3 wires that run to the TPS directly to the computer board, had to take apart the PCM to do that.

I recently installed a charge relay and for the ends I had some copper lugs, but no crimper.
So I took a tubing flare tool. separated the 2 halves.
pushed the #4 gauge wire into the copper lug
Laid the lug on the crescent of the flare tool.
Used a large punch and hammer, smacked it down which secured the wire tight in the lug.
Then I soldered it using a torch.
Then if covered in heat shrink tubing.

Instead of a lug, a rectangular flat tool maybe a broad large screw driver would also work.
the flare tool cradled the copper lug, anyway it worked well for me.

wwestman said:

.......... As to a fuse, have not seen one, plans do not show one, and the first two or more feet of the cable does not have a fuse. But that is something to investigate. Thanks.

Click to expand...

ABYC requires overcurrent protection in all circuits except the starting circuit. I'm just stating how it is supposed to be. If a previous owner did this install, there's no telling what you will find (or not find). Consider doing it right. The overcurrent protection is supposed to be as close to the source (battery) as possible.

RT Firefly said:

Greetings,
Mr. ww. One thing you might try in conjunction with your "small" wire test, as a last resort, is connect the "small" wires as before and starting at one end, push a small straight pin through the wire insulation to contact the inner copper wire. By moving the straight pin along the wire and testing with your VOM you should be able to isolate the stretch where there may be a break. I'm with the other guys though and think it unlikely that a battery cable is actually broken.

Click to expand...

You can buy a tester with that small pin for piercing the insulation for testing purposes but only a hack would intentionally pierce the insulation of a wire or cable, especially on a boat. I would fire anyone who tried that on my boat.

It would be simple to feel along a cable to find a broken spot but it's highly unlikely that a battery cable would break internally. Remember it's made up of hundreds of small wires.

78puget-trawler said:

Every man to his trade.. call a marine electrician.

Click to expand...

Yep, we all need to understand our limits and call in a pro when necessary. When I was working I often had to undo the attempts at repairs by amateurs before I could tackle the original problem.

I've seen but never used one of these - might be worth a try

Wire Tracer Kit

Underground / Buried Tracer Kit

Lots of videos of how to use these

Bacchus said:

I've seen but never used one of these - might be worth a try

Wire Tracer Kit

Underground / Buried Tracer Kit

Lots of videos of how to use these

Click to expand...

The first one is trade used almost specifically for voice /data cable. Does not work well thru insulation. The second one is what will help the O.P.

This looks more like the sort of tool for 12v DC: (I don't buy Craftsman much since their slide in quality 30 years ago.)

Sears.com

Or a fancier one:

Sears.com

DHeckrotte said:

This looks more like the sort of tool for 12v DC: (I don't buy Craftsman much since their slide in quality 30 years ago.)

Sears.com

Or a fancier one:

Sears.com

Click to expand...

I have one of the second link - and it is simply a DVOM w/ a clamp on Ammeter that does work on DC - but the continuity function is the same as any VOM - it will tell you you have continuity or not but not where the break is - the ammeter won't help as if there in no continuity you can't get any amps to test

Not sure about the first one - not sure how they work - but I'm wondering if the circuit is broken if it will give you any indication where

The ones I linked actually put a signal into the wire to be tested and the unit receives the signal indicating how far it is traveling - As tinped mentioned the second unit is more likely to be of help to you

You're right, Don. 'Ammeter' says it all. 'Voltage Detector' might actually be what it says it is.

First checking for continuity (resistance) on a live DC cable will not work with any DVM. You should be looking for voltage and where it goes away.
Second if you can't trace the cable how do you positively know you have the right end?