Battery bank isn't isolated

[Tunitime]

My 2005 Maxum 3500scr has 2 Switches (a Starboard and a Port) that are 'on' or 'off'. The Starboard is for motor and house. The Port is for engine and genny. When both switches are off I have no power, however when the Port switch is turned on lights and fridge turn on, and naturally when Starboard switch is turned on lights and fridge turn on (which I would expect). I cannot figure out how the voltage on Port bank is getting through. My guess is maybe my primary switch (combiner) is stuck. Is there a way to test this as a possible problem? Could I test something else. Thank you in advance.

[mmwjr]

Are the battery switches off, 1, 2, both and if so where are you setting them. I believe there is a cross setting.

[Tunitime]

Both switches point to off… meaning no housepower. . Switches read on or off as only choices. When turning on port switch I shouldn’t get house lights and fridge but I do. I should only get motor and generator. The only other item that I can think of that might cause port bank to give house power is a faulty combiner switch that might be stuck or something.

[mmwjr]

Originally Posted by Tunitime

Both switches point to off… meaning no housepower. . Switches read on or off as only choices. When turning on port switch I shouldn’t get house lights and fridge but I do. I should only get motor and generator. The only other item that I can think of that might cause port bank to give house power is a faulty combiner switch that might be stuck or something.

Is there a 3rd cross over switch either next to the battery switches or in the DC electrical panel?

[Tunitime]

There’s a switch on does that pulls the 2 banks together for starting. The actual combiner is in engine compartment. Don’t know how to test to see if it’s stuck on or not. Looks nasty and needs cleaning.

[mmwjr]

Originally Posted by Tunitime

There’s a switch on does that pulls the 2 banks together for starting. The actual combiner is in engine compartment. Don’t know how to test to see if it’s stuck on or not. Looks nasty and needs cleaning.

Can you post a picture of it?

[Tunitime]

Found in engine compartment on ceiling above battery switches.

[mmwjr]

Originally Posted by Tunitime

Found in engine compartment on ceiling above battery switches.

That seems to be a solenoid but I’ve never seen one like it. Can you post a picture of the other side? Is there 12V on both of the big red wires? The smaller wires would be for the coil of the solenoid so there must be a switch somewhere to activate it. Is there 12V on the small red wire?

[Tunitime]

I’ll have to take pictures and get back to you. I think the small wires go to the dash switch that pulls the battery banks together if I need to start a weak battery.

[mmwjr]

You could temporarily remove one of the big red wires to see if the cross over goes away but be sure to wrap the disconnected wire with electrical tape so it doesn’t short to anything. With it disconnected and power off ohm across the two large terminals to see if they are shorted.

[Tunitime]

Attached is back side iof solinoid and pic of switch bank switches

[mmwjr]

With both battery switches on Measure between the small yellow and red wires to see if 12V is present, it should be there only when the helm switch is pressed. If voltage when not pressed verify the helm switch isn’t shorted. No voltage turn off batteries and ohm across the two large red wires, should be open.

[Tunitime]

Yes it works like you say.

[mmwjr]

Originally Posted by Tunitime

Yes it works like you say.

Did you make the measurements I mentioned? Without them we are guessing that it’s working correctly.

[Tunitime]

I’m getting almost 13v (0ld meter with pointer) when switch is pressed and open on ohm test. I’m leaving port cable off for now.

[mmwjr]

Originally Posted by Tunitime

I’m getting almost 13v (0ld meter with pointer) when switch is pressed and open on ohm test. I’m leaving port cable off for now.

You lost me. Measuring 13V would not be an ohm test but a voltage test. However if you are getting voltage on both sides of the solenoid with the port cable removed then the solenoid is shorted and needs to be replaced.

Since you have the port cable disconnected has the crossover condition gone away from the first post?

[Tunitime]

I'm going to step back for the weekend and unload my brain filled battery issue. I will start again Monday with solenoid issue.

[Tunitime]

Well, I measured between the yellow and red wires and there was no 12v present, but I did get 12v when the dash switch was pressed. Now I thought I would turn off 110v power, turn off all sub panel breakers and see what happens to the 2 battery banks. I'm starting with a weak house bank (12.25) and Engine bank (13.17). I'll compare readings in the morning.

[mmwjr]

Originally Posted by Tunitime

Well, I measured between the yellow and red wires and there was no 12v present, but I did get 12v when the dash switch was pressed. Now I thought I would turn off 110v power, turn off all sub panel breakers and see what happens to the 2 battery banks. I'm starting with a weak house bank (12.25) and Engine bank (13.17). I'll compare readings in the morning.

Ok that means the helm switch is good. I would remove one of the big red wires and see if there is 12V on the terminal it came from, if so the solenoid is bad.

[Tunitime]

I removed 1 red wire from the terminal and did not get 12v from the stud. I'm going to leave it disconnected for now because I need to still find out how my port bank is draining(engine, generator, and charging wire only connected to positive battery terminal). I turned off the charger and took a read of 13.14 volts. The next morning I tested and have 12.58, which I figured it settled down after stopping the charger. This afternoon I tested and now have 12.51. Going to give it a few days