120V Battery Charger Switch turning on a 12v stereo power circuit

[cjwagner1962]

HI all, hoping you can help sort out this electrical gremlin.
2003 Chaparral Signature 240.
Interstate Flooded Cell #1 starting and #2 deep cycle house. new May 2018.
Battery Charger Pro Mariner Pronautic 1230 P installed 2018.
Fusion Stereo installed 2017 on NMEA 2000 backbone.
Guest 2433 P Galvanic isolator. Probably original.
The boat only has 300 hours on it. It is not wet slipped. Most wiring is factory except the NEMA backbone and drops I installed a couple of years ago.
Last trip out we were overnighting at a marina, hooked to shore power. Woke up to nearly dead batteries. Battery charger was in fault mode. Took the boat for a cruise and batteries charged through the altenator no problem.
Got the boat home and found a bad inline 60A 32V glass fuse between the battery charger negative output and the battery ground post. The fuse wasn't blown, just didn't have continuity. Replaced it and the battery charger seems fine now but here is the weird thing.
The stereo and galvanic isolator are located in the 120V cabinet. These are the only 2 devices in that cabinet that need 12V power. From the factory, the stereo 12v and the galvanic isolator 12V positive are crimped to the 12V positive coming from the helm 12V fuse block. This positive power wire does not get power unless I have 120V shore power plugged in and the battery charger 120V switch is on. If I turn off the battery charger 120V switch, I loose 12v power to this postitive power lead. This does not effect any other 12V systems on the boat. I don't believe its a direct short circuit or the 120v power would have surely blown up the stereo and galvanic isolator.
.
Please give me troubleshooting steps.
Thanks in advance.
Chris

 

[alldodge]

Normally you don't find a fuse on the Negative, if it blows or loses connection (as it did) then return power may find another route which could place an unexpected heavy load on smaller conductors.

galvanic isolator 12V positive are crimped to the 12V positive coming from the helm 12V fuse block.

A galvanic isolator is installed on the 120VAC Ground, have not seen one on a 12V positive feed. With 12V available only when charger is ON, this is more then likely a isolator (Diode), which allows DC to flow in only one direction.

Is your issue the stereo is not getting power unless the charger is ON, or something else?

 

[cjwagner1962]

Normally you don't find a fuse on the Negative, if it blows or loses connection (as it did) then return power may find another route which could place an unexpected heavy load on smaller conductors.



A galvanic isolator is installed on the 120VAC Ground, have not seen one on a 12V positive feed. With 12V available only when charger is ON, this is more then likely a isolator (Diode), which allows DC to flow in only one direction.

Is your issue the stereo is not getting power unless the charger is ON, or something else?

alldodge, thanks for responding.
I'm not sure why the fuse is there. I believe it was factory wiring. Its a fancy fuse holder with the clear plastic case around it like you would see protecting a high output car stereo. It is directly in line from the negative output of the battery charger to the negative battery post.
The galvanic isolator main connections are in series with the 120v main in ground from shore power before any other 120V. The 12V going to the galvanic isolator is a spade connector on a spade tab. Next to it are spade 2 tabs/connectors that run to the fault and normal remote led indicator. I assume this 12V + is to run the LEDs. There is also a common spade connector that runs to common 120v.

This 12V+ is also connected to the stereo permanent + as it was from the factory. When I shut off the 120v battery charger switch, the LEDs on the galvanic isolator go off. I don't know if the galvanic isolator is still working at this point. The stereo also goes off. Mind boggling. I guess my problem is that I have no stereo if I'm not connected to shore power. Also, this is a new phenomena and I'd like to find the culprit.

I posted a pic of the galvanic isolator wiring diagram from the manual.

Thanks again.

 

[alldodge]

It is an isolator (called that) but not the ones I'm use to seeing. For me its something used to tell you if its safe to use. Isolator's I'm use to seeing are connected inline with shore power ground.

The LED should go off when 120VAC is removed

To clarify, what is the current problem??
Edit: disregard, 12V goes off on the stereo

 

[alldodge]

Guess I need to see the wiring and don't think pics will do it

You said

galvanic isolator main connections are in series with the 120v main in ground from shore power before any other 120V.

Its series and not parallel?
If it is series (like my above pic) then this is the one in your pic above?

The stereo should be wired after a fuse/breaker, having it powered by feed coming from the bat charger would say that the isolator listed in your pic above may be the issue. It may allow back feeding of 12V but I'm guessing because I don't see the wiring and circuity

 

[cjwagner1962]

Guess I need to see the wiring and don't think pics will do it

You said


Its series and not parallel?
If it is series (like my above pic) then this is the one in your pic above?

The stereo should be wired after a fuse/breaker, having it powered by feed coming from the bat charger would say that the isolator listed in your pic above may be the issue. It may allow back feeding of 12V but I'm guessing because I don't see the wiring and circuity

I am going to disconnect the main grounds to the galvanic isolator and splice them together. Then I am going to disconnect the 12v + and 115V common from the galvanic isolator. If that doesnt fix the problem, then I know its not the galvanic isolator. What do you think? I gotta start this process of elimination. After that, I'll do the same thing with the batter charger. Then I'll do it with the refrigerator. I don't know of any other devices that have both 120V and 12V.

 

[alldodge]

Been rolling this around in my pea brain and I don't see what you just mentioned having anything to do with the issue. As you said in first post:

the stereo 12v and the galvanic isolator 12V positive are crimped to the 12V positive coming from the helm 12V fuse block. This positive power wire does not get power unless I have 120V shore power plugged in and the battery charger 120V switch is on.

Now this is the issue. Everything comes ON when charger is turned ON because its feeding the stereo and isolator, but its also back-feeding the fuse block.

Start at the fuse block and find out why 12V is not present with charger OFF