No DC power at all.

[Soulshine]

Asking for a friend.

The boat is a 1989 Chris Craft Amerosport 370 with twin 7.4 Crusaders.

He brought it home on the water. A trip of about 50 miles with no incident, docked it and a few days later had no working 12 volt items at all. It’s as if the batteries have been removed...nothing.

I checked every breaker in all panels and found nothing amiss. He had the original, hand drawn schematic that did not show any breakers in the ER and I found none anywhere except in the panel in the salon.

The on board battery charger is newer and functioning, new batteries installed and fully charged.

The boat is stone cold dead as far as the 12 volt system goes but all shore power systems are fully functional.

Any ideas? I was expecting to find something obvious since this came on so suddenly but struck out.

 

[dwna1a]

Is the breaker bad?

 

[Soulshine]

Is the breaker bad?

That’s about all I can think of having time to digest things a bit.

There’s only one main 12 volt breaker so that’s certainly possible. I did cycle it a few times almost hoping to hear or feel that crunchy sound a bad breaker will make sometimes.

I have a few spares and should give that a try but even if that’s true the bilge pumps should run, no?

 

[Henry Boyd]

Could there be a 12 volt master switch the owner’s forgotten about?

 

[ttmott]

Does the bilge pump operate?
Bilge pumps are not switched so if there is power in the battery then the pump should operate.
These types of issues typically find their source in the grounds.

 

[dwna1a]

Don't fuss at me for this one, Battery Switchs are on right?
If they are off nothing in the 12V system will work.

Bilge pumps are in their own little world, don't use them as your guild.

 

[Soulshine]

Don't fuss at me for this one, Battery Switchs are on right?
If they are off nothing in the 12V system will work.

Bilge pumps are in their own little world, don't use them as your guild.

No fuss at all.

Battery switches are on and were even tried in various configurations.

Bilge pumps don’t operate manually or automatically.

As I said it’s as if the batteries were removed. Connections checked for orientation and tightness and were OK.

The main 12 volt breaker makes sense until you add the inoperative bulge pumps into the equation.

I’m going to look at the main ground to the block(s) and should have already.

I tried to call the guy today and left a VM, but haven’t heard a word in contrast to the half dozen calls I got over the weekend.

 

[Soulshine]

Could there be a 12 volt master switch the owner’s forgotten about?

I looked everywhere that I could fit and see and found nothing. Nothing on the factory schematic either.

 

[Henry Boyd]

Look I’m just spitballing here, so go easy, but makes no sense. Is the battery charger currently charging? How is the charger wired to the batteries? I assume it’s ok because you said the charger looks newer and seems to be charging the batteries.

Could there be a circuit switch where the batteries are taken off line to allow the charger to work? I’m thinking something similar to what you see between shore power and generator. To energize the 110 only one can be connected. I don’t know why any one would do this, but I find it odd that there is no 12 dc working on the boat, but the charger is plugging away keeping the batteries up.

The other thought is that somewhere in bringing the shore power on line, the dc side was/is locked out. The boat was running fine not on shore power and on engines and batteries. The 7.4 crusaders may be old school iron, but even they won’t run without a good source of 12 vdc, and functioning ground system, so the batteries were working to get the boat home.

Any thoughts anyone?

 

[Carpediem44DB]

I am with T Mott. The problem is probably at the ground. One needs to take a Multimeter to each leg of the 12 V circuit from the positive pole at the battery thru the entire system and find out where the voltage/current stops. Can be time consuming but the only way to isolate the problem.
Good Luck with that.
Carpe Diem

 

[Soulshine]

Look I’m just spitballing here, so go easy, but makes no sense. Is the battery charger currently charging? How is the charger wired to the batteries? I assume it’s ok because you said the charger looks newer and seems to be charging the batteries.

Could there be a circuit switch where the batteries are taken off line to allow the charger to work? I’m thinking something similar to what you see between shore power and generator. To energize the 110 only one can be connected. I don’t know why any one would do this, but I find it odd that there is no 12 dc working on the boat, but the charger is plugging away keeping the batteries up.

The other thought is that somewhere in bringing the shore power on line, the dc side was/is locked out. The boat was running fine not on shore power and on engines and batteries. The 7.4 crusaders may be old school iron, but even they won’t run without a good source of 12 vdc, and functioning ground system, so the batteries were working to get the boat home.

Any thoughts anyone?

I’m as easy as pie Henry and I appreciate the time you’ve taken to respond.

The charger is connected correctly, is set correctly and the batteries have plenty of power available.

I think the main ground is suspect here.

I really just tagged along with a buddy who knows the owner because it’s one of my favorite boat models. You can guess the rest.

 

[Henry Boyd]

I am with T Mott. The problem is probably at the ground. One needs to take a Multimeter to each leg of the 12 V circuit from the positive pole at the battery thru the entire system and find out where the voltage/current stops. Can be time consuming but the only way to isolate the problem.
Good Luck with that.
Carpe Diem

I started with approach originally, but I eventually discarded it. The thing is there has to be a global ground fault. Because it appears all the dc circuits are open. Except for one; the dc circuit associated with the battery charger.

Boat chargers are not connected like automotive charges. The charger negative is connected to the ground system, and then a from the positive, a hot lead goes to each positive battery terminal, or more precisely, the positive terminal on the battery switch that is connected to the line running to the actual positive battery terminal for each battery, or linked batteries. This arrangement allows the batteries to be charged regardless of how the Switch is set. But for this to work there can not be an open circuit to the ground connecting the negative terminal on the batteries to the negative of the charger.