Lost of all DC power

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H

hfmckevitt

Veteran Member
Joined
Oct 24, 2015
Messages
68
Location
USA
Vessel Name
Linda Lee
Vessel Make
45' Aquarius motoryacht
Today when I went to the boat I notice that all the DC was not working.
I check the main circuit breaker, it was good. The batteries are fully charged. My AC is working. All fusses are good.
The boat is a 45' 1990 Aquarius, with 2 30amp service, 3 12volt batteries.
Can figure it out, any ideas?

Henry
Linda Lee
 
Check voltage at your batteries

Start at the begining, check battery voltage at your batteries , should have 13 +volts. Check for a inline fuse , should have one with in 18" of your positive terminal on your house bank. Check and see if house battery switch is on. Check voltage through the switch. Check your breaker panel for a master switch or breaker. Check for voltage to the panel . if you have a battery combiner or isolated confirm voltage in and out. You should find your problem.
 
How did you determine the batteries are fully charged?
Did you check the battery switch?
Doe any continuity checks twixt batteries and main panel?
 
Greetings,
Mr. hf. Before you go all nuts, check and clean your connections particularly your grounds. You can check with a meter AS you clean connections starting at the batteries.
 
Some boats have a breaker fuse close to the battery, and at the main power panel. Also check battery terminal.


True story

When we first bought the boat, changed fuel filter. Being a newby did not have about air in the fuel line. Well the diesel engine died. While cranking the engine lost the DC power. :eek: To make matters worse we were being blown into the lake Union police dock. We finally found the blown fuse but not a spare fuse. Well we did gey blown into the police dock, causing some excitement. :hide:

However the police where some what freindly and helpful got the boat started. Anyway that was our introduction to the lake union police. :flowers:
 
Last edited:
RT Firefly said:
Greetings,
...check and clean your connections particularly your grounds.
Click to expand...

:thumb:

Then start at the beginning (+ term) & verify V through a complete circuit.

Is this House DC - Eng Start DC or both?


Batt'y switches sometimes fail (open) operate sw several times & try different conditions. If Sw - I can probably find the link (w/ pics) of the poster that chased charging problem and finally found the problem in the 1-2-All - Off Sw

Also probably better to post this in Electrical, Electronic, Nav section vs here - maybe a Mod would move it if you asked?
 
Last edited:
Follow a couple of the negative (black wires). Do they all connect through a bus (all connected to a metal bar)?
 
Great advice above. Agree with starting at battery voltage (not the leads...the battery posts) and working out from there with the leads, bus, fuses, sub-bus, etc.

I'd suspect a main ground also.
 
My suggestion is a bit different.

Do not even think of taking anything apart for cleaning or otherwise. The reason is simple. Anything you do introduces the chance of error.

Troubleshoot the problem using a voltmeter. Start at the batteries, and work towards the panel.
 
ksanders said:
My suggestion is a bit different.

Do not even think of taking anything apart for cleaning or otherwise. The reason is simple. Anything you do introduces the chance of error.

Troubleshoot the problem using a voltmeter. Start at the batteries, and work towards the panel.
Click to expand...

I agree. If I was to start taking things apart to "fix" them. I would certainly screw things up. Follow the current and find the problem. You know it has to be someplace that affects the entire DC system. So I would start with the ground connection and make sure you have continuity back to the battery, then go from there out to the DC panel.
 
Capt.Bill11 said:
It sounds like a bad ground issue to me.
Click to expand...

Yep, everything is a bad ground issue. :banghead:

There are two parts to a DC electrical circuit, positive and negative ("ground"). A fault in either will disconnect the circuit. Since the fuses, circuit breakers and switches are in the positive part of the circuit, it's naturally more likely that the fault is in the positive side.

To the OP: As has been suggested, start with the batteries, Check the voltage there, then follow the cables and check at every connection point, fuse, circuit breaker, etc. Don't take anything apart. Wiggle the cables at the connections to determine if they are loose.

I'm guessing that you have limited electrical skills or you wouldn't have posted here so if you can't figure this out yourself, bring in a pro. Don't make things worse by disconnecting or moving wires.


BTW: There should be a fuse (usually) or circuit breaker in the positive DC cable from the house batteries within a few inches or perhaps a couple of feet from the positive connection to the batteries. This will be a large fuse, a few hundred amps. Check this. Check the voltage to ground from each side of the fuse or circuit breaker. If none of your DC appliances work, the trouble is between the batteries and the DC circuit panel or the main DC breaker in the panel. Or the ground.
 
Last edited:
WesK said:
Yep, everything is a bad ground issue. :banghead:
Click to expand...

Well, at least you got that right. :D

But seriously, it could very well be a positive issue. But in my experience it's more often than not a ground problem.

Obviously you need to check both sides.
 
Check near your panel to see if there might be a regular old cartridge fuse or two with two 30A circuits. Pull fuse and check continuity. This might be the easiest first thing to look for.
 
Greetings,
Regarding the cleaning of connections: I am NOT suggesting Mr. hf start disconnecting wiring willy-nilly. Taking one wire off at a time and cleaning the connecting surfaces well with either sandpaper or a wire brush, coating with a dielectric grease and reconnecting is NOT rocket science.

IMO this exercise will accomplish 2 things. One: It will provide more of a familiarity with the DC electrical system that Mr. hf will most definitely benefit from and two: It will perform what may be a delayed/forgotten/neglected maintenance issue. Both good things.
 
Capt.Bill11 said:
Well, at least you got that right. :D

But seriously, it could very well be a positive issue. But in my experience it's more often than not a ground problem.

Obviously you need to check both sides.
Click to expand...

Come on Capt Bill.....:D

Just because all too many boats have the negative ground buss as 25 wires with various sized ring terminals to a 3/8 or 1/2 inch bolt in the bilge...doesn't mean it should automatically be suspect. :facepalm:

Then again...sometimes that's one of the best parts of boat electrical systems.....:nonono:
 
bilge53 said:
Check near your panel to see if there might be a regular old cartridge fuse or two with two 30A circuits. Pull fuse and check continuity. This might be the easiest first thing to look for.
Click to expand...

Fuses for the DC power will be more like 300 amps, not 30 amps and located near the battery so as to protect the conductors feeding the panel.
 
bayview said:
99% of the time the batteries are dead.


verify that is not the case before doing anything else
Click to expand...

The OP posted that they were fully charged but you are correct, they should be checked. Checked with a volt meter and a load, not just open circuit.
 
"Fuses for the DC power will be more like 300 amps, not 30 amps and located near the battery so as to protect the conductors feeding the panel."

# 2 finger missed a "0". Thanks
 
Thank you everyone. I found the problem. I locate a bad fuse. It was buried under the wires where I could not see it at first.

Thank you
Henry
 
Wow! Problem found closure post! Good job.:thumb:
 
Or the fuse just retired. Jack pot!
 
sdowney717 said:
Sometimes they get old and they just die.
Click to expand...
That would be pretty rare. Even more rare considering that it apparently failed while the boat was idle.

It might remain a mystery as to why the fuse failed but it would be a good idea to have a spare on hand just in case there actually is a reason.
 
So how common are blown fuses without a Paul Harvey moment showing up?
 
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