DC power poblem

[spincycle]

when I leave the dock and disconnect my shore power and don't run the genny, my 12 volt Dc system does not power any of my depth or VHF, etc systems. Is there a switch I need to turn?, the light on my 12 volt dc panel is burned out, so I can't tell if there is any power there.

Spincycle

 

[CapetaniosG]

Spincycle: Open the 12v panel and take a voltmeter and see if you have power at the panel. Normally there is no switch between the power source (your battery) and the panel. If understood you correctly, your 12v powered instruments work while you're plugged in to shore power but do not when unplugged. That would suggest to me that your 12v instruments may be powered by a step down transformer that steps down the 120v AC to 12v DC.
It would be a strange set up, but never underestimate the ingenuity of some boat owners. You also may want to trace the power wires from your 12v istruments and see where they take you. Good luck.

CapetaniosG

 

[spincycle]

if it is a step down transformer, is there a switch I need to throw to put the 12 volt online? the boat is a 54 hatt. with a 24 volt DC sytem. in the pilot house there is the panel that says dc systems and them underneth that panel in the same door is a DC panel labeled electronics, in it is about 16 breakers all individually labelled for each item,garmin, radar,seatel,depth, etc., it's all original Hatt stuff.

Spincycle

 

[Brian Degulis]

First you need to figure out what's powering the 12 V system? Do you have a seperate 12V battery with it's own charger? If so the battery may be shot so when the charger is not on no power. Or you may have a 120V power supply if that's the case then you need shore power or gen to make the 12V.

Brian

 

[CapetaniosG]

If the electronics work while you are plugged into shorepower without flipping a switch, why would there be a switch when you are not plugged in? It makes no sense. Do you flip a switch when you're plugged in? The answer is No. If there was a switch in the OFF position say the instruments would have no power when you're plugged in. But that's not the case since those instruments are powered while you're plugged in. I'm sure thre is no switch.

As stated above, you have to find the power source of your DC instruments. It has to come from a battery or a step down transformer. A good place to start is to review your boat electrical (DC) drawings and make sure you understand what they show. Normally the wires are numbered at both ends ie. start and termination and should be easy to identify.

CapetaniosG

 

[REBrueckner]

Tracing the power lead positive wire is the way to go....a tone generator may be helpful for that....I believe Radio Shack carries modestly priced tone gens and detectors...one part puts an audio tone on a wire, the receiver picks it up so you can find the other end...

 

[spincycle]

o.K, opened the Bottom DC electrical panel and got out my volt meter, here is what I have founjd out. left side of this panel is 24 volts, controls auto pilot, radar and DC stereo package. the other side is the 12 volt side and when tested it only reads 9 volts at the main with all other breakers shut off. shore power is also shut off. what is the power supply to this side of the panel when shore power is off.

Spincycle

 

[CapetaniosG]

Based on what you stated in your last post, it appears to me that the power comes from a 12v DEAD battery located somewhere in your boat. You must locate that battery. When you do, that is your power source.

CapetaniosG

 

[MikeP]

I agree w/Cap G; in addition to a "hidden" batt, there is quite possibly a "hidden" 12v ac powered charger that charges the batt/provides power when shore is connected. It doesn't seem likely that a voltage converter (24 to 12vdc) is used if there is a 12v circuit panel. Voltage converters are usually used close to the item that needs the lower voltage - such as at the helm position to operate a helm instruments/lights.

Let us know how this turns out! Good Luck.

 

[REBrueckner]

Mike and CptnG are right on..very unlikely a converter failed at 9 volts which is about what a DEAD 12 volt battery reads...its much more likely there is a dead 12 volt battery, maybe partially dried out, maybe dead because a charger is off or defective....

 

[SeaEric]

I am recently aquainted with a 1991 Hatt 52 CPMY, having been involved in the survey/seatrial and subsequent sale. That boat has only one helm station- the flybridge. Inside the port side cabinetry on the bridge is a 12v. battery, specific to the nav electronics. Since that boat has a fair amount of 24v components like spin's does, this story was starting to make sense.

As suggested, there must be a 12v (dead) battery hiding somewhere that is intended to power up your electronics. If your boat was recently purchased, perhaps this system is referenced in your pre-purchase survey. It sure should have been.

 

[spincycle]

i will try and trace the wires back in side the bulk heads, but, the power cable that supplies this 12 volt side of the panel is not original hatteras. it's not on any of the original electrical plans. i have the original owners book and there is not even any mention of a 12 volt system originally installed in the boat. the panel labels on the 12 volt side of the 24 volt panel are not original either. There is no sign of a battery box in my bridge or helm area. i have the two original double batt boxes in the engine room and two up front for my bow thruster, and it looks like two in were my genny is, but all those batts are working fine. No mention of it in the survey either. obviously was not detected or checked or the batt just went dead the last few months, (possible)
I agree, sounds like a dead batt, but were do i look for this thing?

spincycle

 

[SeaEric]

Perhaps there is a way to contact the previous owner, or the yard where the boat was kept/maintained. Someone must know the answer. Before you go at the boat with a sawsall, I'd get on the horn to the PO/broker/yard/surveyor.

 

[Pascal]

trying to remember... isnt' there a 12v battery that powers the electronics? either under the flybridge helm, or behing the lower helm, next to the computer.

i really sounds like a dead battery. did you check the wiring diagram ?

 

[spincycle]

there is an inverter behind the helm to power the nav. computer but no battery, trust me i crawled in there this weekend. i really don't know were it could be. There is nothing on any wiring diagrhams about even a 12 volt system.
I called the broker who also maintained the boat for 5 years, let's see what he has to say......

Spincycle

 

[CapetaniosG]

Normally an transformer or an inverter is labeled X volts in Y volts out. What does yours show? Is it 24v in and 12v out? If it is, then I would venture to say that could very well be your power source for the 12v. Such transformers do have an on/off switch and light indicator but not always. Look at yours and see what it says. If this transformer is the 12v power source and it shows 24v in and 12 out then it would seem to me that the input voltage comes from your 24v system. Have you checked your 24v system to make sure is up to par? Hope you resolve it soon and keep us posted.

capetaniosG

 

[Brian Degulis]

there is an inverter behind the helm to power the nav. computer but no battery, trust me i crawled in there this weekend. i really don't know were it could be. There is nothing on any wiring diagrhams about even a 12 volt system.
I called the broker who also maintained the boat for 5 years, let's see what he has to say......

Spincycle

Ok now you have to determine if the inverter or power supply is powered by the boats 24V system or the boats 120V system. If it's the 120V system then your not going to have 12V without gen or shore power. If it's the 24V system and it has 24V getting to it and only 9v coming out the power supply is bad.

Brian

 

[spincycle]

the inverter benind the helm was put in by the previous owner to power only the 110 volt computer and that is the only item hooked up to this 110 power coming out of the inverter. is there a way that this inverter also steps the 24 volts down to 12 volts as well as steps the 24 volts up to 110. i would not think so, it's an inverter, it onl;y goes one way. 24 to 110, yes, but not 24 to 110 and also has dual capability to take the 24 to 12?
i have nad the power switch off on the inverter while at the dock so it can't be part of the electrical circuit, for i am still getting 9 volts at the panel.
Back to looking for the battery......

Spincycle

 

[spincycle]

I have found the battery that controls only the 12 volt system, it was in the genny room. i tought it was for starting the generator and when the generator was always starting you would tend to belive the batt would be o.k. After tracing the wires from the batt box, they went to the 12 volt portion of the panel i had mentioned that controlled electronics. Well after close inspection for the battery and charger, I discovered the battery was bone dry, no water in the cells. It is my belife that this battery is dead and cooked, but i filled it with distilled water anyway and turned on the charger.
with in an hour, I turned off the charger to see if she was holding a charge or not, and it was, there was enough power already to keep my electronics on i left it on for about 5 minutes, so i turned the charger back on. lets see what happens next time i take her out and just run on the batts.

 

[CapetaniosG]

Congratulations!!!! You found the battery. That's good. Enjoy your boating.

CapetaniosG