Very Baffling electrical problem

[RLewis]

Ok- I will try to be very succint and clear- but first I will admit that I am a novice and very much in the learning phase.
The boat is 3 months new to me and is vintage 1981
I have 2 12volt batteries and a master battey switch.
For the time I have owned the boat all the electrical has worked fine. My mechanic says the alternator is producing power, checked wirth his meter a month ago. The battery charger hooked to shore power is keeping the system topped off.

Today I needed to move the boat from one marina to another. The weather was not so good and ultimately we had to turn back and until I get this resolved I am now paying double moorage- so Please any help will be greatly appreciated.

At the start of the day all was fine and the 12 volt system worked- cabin lights, VHF, water pump were used and worked fine (this was after shore power was disconnected)

Half way through this ill fated day I noticed that the VHF was quite. Shortly after we were back in the slip and discovered the following.

I have no 12 volt system- Cabin lights, water pump, bilge pump, VHF CD stereo nothing-
Now the bilge pump is wired in such a way the independant of the switch on the control panel, should the water in the bilge rise and trigger the float switch- the bilge pump would engage and pump the bilge. I cannot manually make the bilge pump work either from the switch on the panel or by manually activiating the float switch.
Interestingly enough- the 12 volt outlets work when the switch on the control panel for them is switched on. One at the helm and one outlet at the nav station. These will go dead when the switch marked 12 volt outlets on the panel is turned off.

So at least one switch in the panel seems to be working.

I metered the batteries and each reads 12 volts.
I checked the main battery switch and all connections seem fine.
The inital inspection of the wiring in the engine compartment seems fine- I have seen no breaks or loose wires.
My mechanic earlier installed a terminal block to correctly tidy up some wiring from the previous owner who had connected things directly to the battery terminals- since this install all the system has been working fine as stated above and in checking all the contacts here - they all seem fine. Been fine for the last month.

While underway back to the slip and was below in the cabin I did notice that the volt meter in the face of the panel was cycling from zero to less than 10 volts and was giving off an audible beep. This to me says that its a low voltage alarm and was acting correctly as the voltage reading was erradict.
So to me it would seem that if the batteries have power but the panel does not - then the problem must be somewhere in the wiring (?) from the batteries and the battery switch to the control panel.
Does this makes sense?
Why would it suddenly quit?

Granted the water was very rough and Yanmar 30 hp diesel was not allowing us to make much headway with high winds and at the same time going against the tide- hence the decision to turn back.

We did get jostled around some- but I cannot think of or could find anything that got moved or disconnected by the motion of the boat in the waves.

What am I missing? I am not an electrician but my common reasoning is telling me that the problem has to be in the control panel or the wiring from there back to the batteries. I cannot imagine that the wiring runs through the boat to each light could have all gone bad downstream of the panel.

Could the actual volt meter indicator dial in the panel be a possible source of my problem?
Could it actually be getting full power from the alternator but somehow going bad internally and registering low voltage hence the alarm and voltage cycling?
And if it was failing and did fail- could it cause the rest of the panel to not function and therefore not send the powe flow from the batteries through the panel switches and onto a given fixture?

Could the rough wave action caused a wire to chafe and short out? But if so- why would one breaker switch in the panel function and control the 12 volt outlets?

I am stumped and gave up for the day and will go back tomorrow to the boat to start tracing wires to find a possible problem-
In the meantime I am now paying double moorage as I mentioned above and my other half is no too happy about any of this.

Please Help any suggestions (my mechanic is not back in town until the 7th)

Thanks very much Randy

[Kettlewell]

My initial guess would be a bad ground somewhere, most likely from your battery to your electrical panel. For some reason those outlets that are working may be getting a ground from somewhere else. Clean and check for tightness where all cables connect at the batteries and on the engine.

[sailvayu]

It is really hard to trouble shoot a boat over the Internet but I will say the best approach when trouble shooting things like this is to start at the beginning and work your way through systematically. Start at the batteries and follow the power supply wire to the panel checking each and every connection. check ground as well. As kettlewell said this does sound a bit like a bad ground but you just have to follow the facts. like a good detective you have to follow the leads. The mistake most make is to jump from one place to another and it sounds like you have been doing some of that. Follow it from start to end and you should be able to locate the problem in short order.

[RLewis]

Thanks for the reply- I will double check this tomorrow when I go back.
Although I should mention that in my initial check once back at the slip I did check all terminals and all connections are good. These were tidy up last month when my mechanic cleaned up the previous owners wiring additions.
Randy

[sailvayu]

You have to check them with a volt meter not just a visual inspection which it sounds like you are saying. make sure you have full voltage at all the connections. Helps if there is a load on them as well but if nothing is working that would not be possible. look for a voltage drop on the connections.

[RLewis]

Capt Wayne and kettelwell- so if by starting anf the beginning ie the battery terminals and working my way down stream and following the battery leads to the panel- assume I cant find any fault in the wiring- could the issue be with the voltage indicator in the panel?

not meaning to jump ahead and will certainly follow your advice tomorrow for the wiring, tho I will not be able to actually see some of it as it is concealed internally in bulkhead or at some point in a place unable to be seen under the floor boards- can one assume that the solid stretch of wire would be ok?
Lets say it chafed through at some point and was bare wire contacting the hull- would that be a ground if the hull or say a bulkhead is of fiberglass or wood-? Wouldnt you have to ground to metal?

This is where is get lost with electrical- but thanks for helping to educate me
Randy

[RLewis]

Capt Wayne sorry I should have stated correctly that I did use my multi tester on the batteries when checking the connections and each registered 12 volts although to be correct there was no load on them as you mention as nothing is working.
Randy

[Adamante]

Step 1, find out why the bilge pump isn't working. If you are measuring 12+ volts at the battery, see if you are getting the same reading at the bilge pump float switch. If yes, but the pump won't run, you have a bad float switch or a bad pump.

If there is no voltage at the pump (or the float switch), trace both wires from the battery to the bilge pump and see where the voltage is interrupted. This should be fairly simple.

Step 2, start tracing the wires from the battery to the electrical panel and measure the voltage along the way, referencing to the common ground. Eventually you should find the place where the voltage is interrupted.

[RLewis]

Adamante and all this is great advice I will hopefully get some resoultion on this tomorrow.

Thanks for the info and thanks to anyone else that may reply- this forum is a great place to learn and much appreciated
Randy

[sailvayu]

It is possible the meter is showing wrong you can check that too with your multi meter. It is always possible a wire got broken along its length but to be honest in 40 years working on boats i can count on my fingers the number of times i have seen that. it is almost always at a termination point. If the whole panel is out you have to have a loss somewhere before the panel. When you say I have no 12 volt system are you saying you have no 12 volts on the system? maybe I am not fully understanding you

[RLewis]

Capt Wayne- sorry- to clarify when I said I have do not 12 volts on the system- I did mean that the 12 panel is dead and that there is not 12 volts at the panel. It basically is a fold down door and you can easily see the back of each switch. When closed the panel is essentially 2 rows of breaker switches. The top row is all 12 volt related and the lower row is 110volt main hot water heater battey charger.

So when I open the panel and inspect the breakers/switches I was using my multitester and measuring the contacts on the back of each switch where the wires are attached by tabs with machine screws in them.
If I am undestanding the design correctly- each switch has 2 contacts one side is a common red wire and is jumped to all of the individual switches and the other side of each switch has a separate wire on each - and are identified on the panel face as watre pump, bilge pump, salon lights, forward lights, nav lights etc.

The wiring of course originates at the batteries and the leads go to a master switch that has Off,, Bat 1 Bat 2 and Both, and then presumably heads to the panel.
I have to confess that I dont know the boat or the system all that well (but learning) so I hope I am able to convey this info to you correctly.

Thanks again for your patience and help Randy

[Teknav]

Check for continuity in your fuses. To do that, pull one fuse at a time...place your DMM on Resistance (Ohms)...place the leads of your DMM (multimeter) at the top and bottom of your fuse...look at your meter...if you get a beep, the fuse is good (reading on the meter)...if you do not hear a beep/no reading on the meter...the fuse is blown out and needs replacing (fuse might be charred/burned, or no visible intact wire seen through it.) If that is the case, you need to replace the fuse with an identical fuse; do not substitute fuses...if it says 1A, replace it with 1A and with same looks/size. If you have blown out fuses, get an electrician to determine the root cause of this; if you have no background in electronics/electricity. Good luck! Mauritz

[RLewis]

Teknav- your suggestion is on my list for tomorrow- thanks !

[sailvayu]

ok that makes sense and what i thought but just had to know for sure. Find the larger hopefully red wire that feeds the panel and see if it hase 12 vdc. What are you using for a ground when testing? There should be a ground buss bar make sure you are using that to test the panel. you can work from the panel back or from the battery forward but start at one end and work through one step at a time. When trouble shooting it is important to be very systematic or you might miss something. check the ground connections with the positive. a mistake some make is to just use one ground and test the positive in different places. Try to follow both they should run together most of the time.

[RLewis]

Capt Wayne- thanks this makes sense - I have to profess that I dont actually know if the panel has a ground buss bar - but I assume it will have to- if not or if I am unsure could i simply make a ground test lead and say run it to the engine block using an aligato clip?

I will work on testiing both hot and ground leads.

Does it make sense that assuming there was no problem and I opened the panel door and a given switch was in the off position- would you be able to measure 12 volts across the 2 terminlas on that switch?