Electric Confusion? - Need Help!

[rgranger]

Hey All
I've had a graduate level electronics course when I was in graduate school, I've built power supplies and A/D converters etc. .... so I know what end of the soldering iron to hold but this one has me stumped.. If you have any ideas PLEASE HELP.....I've attached a diagram of how I wired my panel in my boat.

Here is my story. Yesterday I want out to check the battery in the boat (it was good) and I tested all of the switches and lights. Everything worked ... but... I noticed that my 2-season old LED bow light was only showing red. The green light was so dim you could hardly see it. It is an Atwood brand and Walmart carries the exact same one (great, I can use the same base) so I unscrewed the one I had from it's base and installed a new one over the same base. Seemed like my luck was holding since I didn't have to re-bed the light... Wired it red-to-red and black-to-black and then things got strange...

None of my switches work now. No juice at all. I tested the voltage at the hot and ground bus and I had 13V. SO LONG AS ALL OF THE SWITCHES WERE OPEN. As soon as I throw a switch (any switch) the voltage drops to zero between the the buses and I get no juice through the circuits to the devices.

I don't get it. Even if the new bow light was shorted, how could it effect the other lines? And if it is not the new bow light, then how did I generate a short in ALL of my lines?

There wasn't an electric storm last night so I fairly certain my boat was not struck by lightning.

I ran out of day light today but tomorrow I'm going to disconnect the new bow light and see if the other lines start working again... and if that works, I still don't get how a short in the nav. light line could effect the other lines if the nav. light switch was open.

If you have any ideas, please share....

r

 

[Ron20324]

Well, for a start, undo what you did that caused the trouble

 

[Dan Johnson]

Recheck all the connections you've just made. It sounds like there is a grounding issue that is shorting across all your circuits when a breaker is activated.

Another thought: once you've disconnected the new bow light, put a meter on each of the leads and on the casing to see if there is a direct short within. Because it's an LED unit, maybe the chinaman that wired it got the polarity wrong and both LED's are not conducting.

 

[Ray Bowles]

I ran into that situtation a few years ago. I had voltage as long as it was at a very very low draw. As soon as any load occured it all went dark. It turned out to be a moist, dirty connection upstream. Cleaned it up and all was well.
Maybe, maybe not, but worth looking into as the repair is cheap.
Ray

 

[rgranger]

I ran into that situtation a few years ago. I had voltage as long as it was at a very very low draw. As soon as any load occured it all went dark. It turned out to be a moist, dirty connection upstream. Cleaned it up and all was well.
Maybe, maybe not, but worth looking into as the repair is cheap.
Ray

Ray

That sounds like what I have. So exactly what do you mean by "upstream". What I don't get is why this happens today...and not yesterday.... and why it happens no matter which switch I throw? If I had a bad connection someplace in a line, then is seems to me that this should only happen when I try to use that line. But it happens if I throw the cabin light switch, the nav lights, the Aux. switch, even the anchor light (which is an unused line at this time). Voltage drops to zero and nothing works. Very strange.

 

[rgranger]

Well, for a start, undo what you did that caused the trouble

Thanks Ron... you're a big help.



Now quoting myself...

.... but tomorrow I'm going to disconnect the new bow light and see if the other lines start working again... and if that works, I still don't get how a short in the nav. light line could effect the other lines if the nav. light switch was open.

 

[Don12364]

You may have TWO problems.
First either a short or other low impedance on the hot side
PLUS
A high impedance prior to the switches. My first guess would be to slacken and re tighten your battery connections, including the negative one(s). Charging causes gassing and gassing brings a mist of acid droplets on to the battery top. Acid droplets cause corrosion of the terminals which then causes a high resistance connection.

If it is not there then try the battery master switch. Cycle it a few times. Next look hard at any in line fuse(s) and cycle any circuit breakers.

These are the quick checks.
Otherwise connect the neg lead of your meter directly to the neg battery post and switch the nav light on. Then, starting from the pos post, work along the system with the meter pos lead noting 12v on each point. Keep going also along the neg line from the light until you get zero volts. The OC will be between the last 12v and the zero.

I guess all the devices you built at school must have worked first time. That way you learn very little about fault finding.
A lifetime of failures is quite character forming.

 

[Dan Hill]

The fact that you loose voltage when any switch is operated tells me your problem is between the panel and power source (battery bank). I use what's called a power probe at work to find this kind of problem, but heres a similar method that will work fine. Purchase or barrow an sealed beam auto headlight. Connect one leg to the ground bus and the other to the positive bus and see if it lights, by the sounds it will for a sec and then go dim. Start with the ground side by moving the wire to the next connection closer to the battery and so on till you find where the bulb will light. Once the bulb lights and burns bright, the problem is between there and the last place you checked. If you make it all the way to the battery on the ground side your ground isn't the problem. Switch to the hot side circuit and do the same. This is called a circuit load test. Good luck!

 

[kenn]

chiming in late to confirm what you've already heard about 4 times now: something 'upstream' (between the panel busses and the batteries) is gone high resistance. Possibilities - battery connections, battery switch, master breaker (if you have one), and any connections along that path.

 

[LloydB]

Based upon your diagram and that your battery has only two wires connected to it.
you made one and only one change to your set up: "so I unscrewed the one I had from it's base and installed a new one over the same base."
my first guess is that your faulty running lights switch will not turn off and you shorted the circuit when installing the new lamp creating an additional 2nd fault(the old lamp may not have been bad in the first place but you didn't say if you tested it after removal) To check this theory remove the fuse from the running light circuit. Turn on your cabin lights as you did before. If no luck now recheck the battery voltage as the battery may now be discharged or the bad (DIRTY) terminals may have quit passing any voltage at any level of current.
For now pull the fuse to the unused AUX circuit until everything is back to normal -it makes a nice place to leave a spare(and find one)
You may not have a voltage problem but instead have a current problem, here is where that incandescent test lamp will come in handy as WrenchBender suggested although most any 12 volt auto lamp with two alligator clips to connect direct to the battery would work.
1.all switches off -- test lamp on full bright 2.switches tested one at a time to see lamp stays bright and voltage stays the same when measured at the buss 3.move the test lamp to the main bus and test the circuits again

 

[Bill Roosa]

You have a degree right?
Boats have DEDICATED grounds. that is to say if you put 12 volts onto the ground wire you get 12 volts on the hot and 12 volts on the ground (when you flip that switch) volts is a measure of the differance in electrical pressure (gage pressure) so when you measure accross the hot and ground they both see 12 volts or 0 volts differance
sometimes it takes genious to see the blinding obivous (course making the mistake myself also helps) My excuse was it was dark and red and black look alot alike when it is dark and the wires are old and fadded.

 

[Squidd]

chiming in late to confirm what you've already heard about 4 times now: something 'upstream' (between the panel busses and the batteries) is gone high resistance. Possibilities - battery connections, battery switch, master breaker (if you have one), and any connections along that path.

+1 bad main connection

 

[rgranger]

Thanks guys.... I'll let you know what I find.

r

 

[Joe2954]

First place I would look is the ground side.