DC Power problem

[gulshome]

Hi All-

I bought a used Sundancer 280 and it has a weird problem. Connected to shore power, everything works (electrically speaking). Turn off shore power, and the engines start no problem, BUT no DC power of any kind. No blower, no lights, no stereo, etc. Battery switch is on, and i have tried it set to 1-both-2 and all combinations and it still doesn't work. All the circuit breakers near the battery switches are fine. No blown fuses I can see on the dashboard, but maybe I don't know where else to look. Any ideas??? Thanks!

 

[bahamabreisus]

I would start replacing all batteries, most DC problems start there

 

[Bucit]

But he said the engines start with no problems. Does your DC voltage equipment work when connected to shore power?

 

[moparlvr4406]

But he said the engines start with no problems. Does your DC voltage equipment work when connected to shore power?

He says it all works on shore power..possible fusible links at starter or alternator ??
just running off of the battery charger on shore power ??

 

[gulshome]

Just to recap - so far I replaced the starboard and house battery - they were old although the previous owner said they had "never been used." BUT the engines crank on first try, and I could stop them then crank several times in a row and no issues - they seem strong enough. I had a mechanic look at it and he thinks the probs are in the dash AND battery charger. He said the charger is putting out 24V, but wouldn't that blow everything - radio, lights, etc.? In any case, are there fusible links near the starter and alternator(s) on this beast? Any 280 know where they could be? anything else I'm missing? I'm stumping most of the locals here and I may not know boats, but I'm pretty good with cars and DC systems in general, and nothing makes sense to me (besides a loose or incorrect wire).

 

[moparlvr4406]

the system is the same as a car besides the dedicated grounds rather than a chassis ground
and a 24v output SHOULD blow every 12v thing in the boat.

 

[mpmiller]

A couple of checks/clarifications to help us troubleshoot.

With shore power connected and battery switches to on and both:
1) Can you turn on the blowers?
2) Can you turn on the radio?
If so, it's not likely your control panel.
3) If you disconnect the shore power CABLE while the radio is on and the blowers are running, do they continue to run? Do the lights on the control pad toggle on/off?
4) Now with the shore power CABLE still disconnected, can you easily start the engines? If so, it's not likely a battery issue.

 

[gulshome]

Thanks for the sanity check. And, sorry I didn't reply to the post below- yes, connected to SHORE power, all the AC AND DC systems work just fine. Disconnect from SHORE power and all DC systems no workie, BUT the engines start just fine. <Stumped>

 

[gulshome]

A couple of checks/clarifications to help us troubleshoot.

With shore power connected and battery switches to on and both:
1) Can you turn on the blowers?
2) Can you turn on the radio?
If so, it's not likely your control panel.
3) If you disconnect the shore power CABLE while the radio is on and the blowers are running, do they continue to run? Do the lights on the control pad toggle on/off?
4) Now with the shore power CABLE still disconnected, can you easily start the engines? If so, it's not likely a battery issue.

Thanks for the help.
1) Yes, shore power on, batteries on (and on 1, or 2, or both) blowers will run
2) Yes, as above
3) Disconnect or turn off shore breaker, while blowers or radio running then all dies
4) Yes, shore power disconn'ed, start engines with no sweat, and stop, and start again, no prob at all

Still stumped. A local mechanic gave me the name of a local boat electrician, I'm ready to call him as of tonight...

 

[Mike Blake]

Thanks for the sanity check. And, sorry I didn't reply to the post below- yes, connected to SHORE power, all the AC AND DC systems work just fine. Disconnect from SHORE power and all DC systems no workie, BUT the engines start just fine. <Stumped>

I'm not getting it either??????????????

 

[mpmiller]

Have you looked to see how the house is wired to the batteries? It almost appears as if they direct wired they direct wired the house to the AC convertor. The simple guess is that this could happen if the positive pole connection was loose or not making a good connection. You should try cleaning the terminals.

The crazy situation would be non standard rewiring. Just curious, do either the blowers work or the engines start with the battery switches set to off when shore power is connected?

 

[gulshome]

So, is it safe to start the engines with the batteries set to off? I'll try it tomorrow when i can go out there. I think the blower does work when connected to shore power and the batteries set to "off."

 

[mpmiller]

The engines shouldn't start with the batteries on off. Also, your blower shouldn't work with the battery switch to off. Only your bilge pumps bypass the switches.

My guess is that it is the house connection to the batteries and will be a simple switch. I can't remember if the AC convertor is wired directly to the batteries or to a distribution bar (I think they are connected to the battery terminal connector). My guess is the issue is somewhere physically between where the AC convertor is connected and the batteries, which would be the terminal itself, or a line feeding a distribution bar (which could be fused).

 

[gulshome]

The engines shouldn't start with the batteries on off. Also, your blower shouldn't work with the battery switch to off. Only your bilge pumps bypass the switches.

My guess is that it is the house connection to the batteries and will be a simple switch. I can't remember if the AC convertor is wired directly to the batteries or to a distribution bar (I think they are connected to the battery terminal connector). My guess is the issue is somewhere physically between where the AC convertor is connected and the batteries, which would be the terminal itself, or a line feeding a distribution bar (which could be fused).

Thank you!

 

[my DOG HOUSE]

Ok, I am going out on a limb here.

My guess is that the problem is a ground issue. The engines are grounded via huge cables as opposed to the rest of the DC system via grounding blocks. The battery charger is probably connected directly to the ground block system, therefore it works on shore power. The problem is probably where the battery DC system connects to the ships DC ground.

With everything off and batteries disconnected, start with a meter and look for continuity from the NEG battery cable at every connection all the way to the boats grounding blocks.

 

[GrandMaster]

Sorry, if I meissed this question/answer already, but do the 12V items work with the shore power disconnected, all battery switches on, and the engines running?

 

[Steve Craig]

The + side of the starter has the cable direct from the battery. Leaving the same terminal you should see a couple smaller conductors with fused links in them. May look like a fuse wrapped up in tape or heat shrink. Open link will disable everything DC on the boat once unhooked from shore. Your shore power equipment may be feeding it from another point.
General rules on older car engines was one fused link for the headlights + one fused link for everything else.

 

[my DOG HOUSE]

The + side of the starter has the cable direct from the battery. Leaving the same terminal you should see a couple smaller conductors with fused links in them. May look like a fuse wrapped up in tape or heat shrink. Open link will disable everything DC on the boat once unhooked from shore. Your shore power equipment may be feeding it from another point.
General rules on older car engines was one fused link for the headlights + one fused link for everything else.

Steve, I had that exact problem with the terminal blocks on the stater. My symptoms from that were that the alternator would not charge, but my DC system continued to work off of residual battery voltage. :smt021 I hate these electrical problems. :huh:

 

[Steve Craig]

Steve, I had that exact problem with the terminal blocks on the stater. My symptoms from that were that the alternator would not charge, but my DC system continued to work off of residual battery voltage. :smt021 I hate these electrical problems. :huh:

First job, when we bought our boat, was to change out the old mis-matched batteries & install a new alternator.
Charging system was showing only +/- 13V at the batteries with the engine at about 2000 RPM.
Load test showed about 10-11V on each battery.
Last thing I wanted was to be stranded due to battery failure.
Being brand new to boating at the time, we had enough "other" worries those first few trips to the ramp !
Gremlins live within the wiring systems on most vessels/vehicles. Sometimes they come out to play.