Half power to some 12volt circuits

[Geosman]

Try removing the fuse that was blown. To see if you have voltage and dim lights with the fuse totally removed. LED s draw so little power that a weak connection that creates resistance may act as a resistor in the circuit resulting in lower voltage to the lights.
If you have no voltage or lights with the fuse removed then problem is solved.
If however, you still find partial voltage then begin sequentially removing and replacing The other fuses until you find the circuit that is cross feeding to the lights. If there is a cross feed; that’s another ball of wax to decipher.

[Wyatt]

Originally Posted by Geosman

Try removing the fuse that was blown. To see if you have voltage and dim lights with the fuse totally removed. LED s draw so little power that a weak connection that creates resistance may act as a resistor in the circuit resulting in lower voltage to the lights.
If you have no voltage or lights with the fuse removed then problem is solved.
If however, you still find partial voltage then begin sequentially removing and replacing The other fuses until you find the circuit that is cross feeding to the lights. If there is a cross feed; that’s another ball of wax to decipher.

Shouldn’t it be, if he removes the fuse, and he still has dim lights, than he removed the wrong fuse?

[Goodspike]

Originally Posted by Wyatt

Shouldn’t it be, if he removes the fuse, and he still has dim lights, than he removed the wrong fuse?

But seemingly the problem was a blown fuse--although my suggestion originally was that it was a bad connection of the (possibly damaged) fuse--not a blown fuse. And I still suspect that's what happened.

I think the new suggestion is that there's some sort of cross feed from another circuit--like a shorted connection but with power rather than ground. I think that's unlikely, but I also thought my own fuse idea was unlikely. But removing the fuse would test that theory.

[GaryT]

I agree, and there may be something else going on besides just the fuse being blown from me shorting the line out. May try to check further if I feel it has other effects.
Out of town at this time, but next check in at RV dealer where I purchased it will bring it to their attention. Also unable to recheck the dimmer and will check that again when back to see if it is still functional. It was a touch sensitive dimmer and the circuitry is probably pretty sensitive to any electrical shock.
Thanks for your input.

[HotMech]

With regard to the low voltage. The new fuse panels. Used in late model coaches are equipped with led lights to indicate a blown fuse. Those lights are wired across the terminals, just as the fuse is. When the fuse is good, current flows through the fuse. When the fuse blows, the current flows though the led circuit. Since the lights in the coach are led. They don't require much current, to light up. Because the led indicator in the fuse box actually is completing the circuit. You will get a small current to the lights connected. If the indicator led, was not there then the lights would not glow. Kerry

[Goodspike]

Originally Posted by HotMech

With regard to the low voltage. The new fuse panels. Used in late model coaches are equipped with led lights to indicate a blown fuse. Those lights are wired across the terminals, just as the fuse is. When the fuse is good, current flows through the fuse. When the fuse blows, the current flows though the led circuit. Since the lights in the coach are led. They don't require much current, to light up. Because the led indicator in the fuse box actually is completing the circuit. You will get a small current to the lights connected. If the indicator led, was not there then the lights would not glow. Kerry

That would actually make a lot of sense! I think we have an answer! Except I'm not following why the LED wouldn't light without the blown fuse. ?????

[Geosman]

I think you got it with the current bypass through the LED indicator light!

The same is true for newer illuminated wall switches for 120 volt circuits. If using Dimmable LED lamp or flood lights the slight current through the light in the switch when the switch is turned off, is sufficient to keep the lights it controls glowing at a very low level. Normally you might not notice it in the daytime but speaking for myself. The dim glow from my kitchen LED can lights makes a comforting night light.
At last there need not be a concern for a voltage cross over issue. Were the switch operating older incandescent bulbs it would not be noticed.

[GaryT]

Originally Posted by HotMech

With regard to the low voltage. The new fuse panels. Used in late model coaches are equipped with led lights to indicate a blown fuse. Those lights are wired across the terminals, just as the fuse is. When the fuse is good, current flows through the fuse. When the fuse blows, the current flows though the led circuit. Since the lights in the coach are led. They don't require much current, to light up. Because the led indicator in the fuse box actually is completing the circuit. You will get a small current to the lights connected. If the indicator led, was not there then the lights would not glow. Kerry

Well that makes me feel better. Or at least explains the situation that I am experiencing.
Since the red indicator lamp is not as bright (with the blown fuse) as the others when I remove the fuse indicates there is some voltage being used in that circuit taking it away from the indicator lamp.
Thanks for the explanation.

[Goodspike]

Originally Posted by GaryT

Well that makes me feel better. Or at least explains the situation that I am experiencing.
Since the red indicator lamp is not as bright (with the blown fuse) as the others when I remove the fuse indicates there is some voltage being used in that circuit taking it away from the indicator lamp.
Thanks for the explanation.

So maybe those are part of the parasitic draw on the batteries????

[Morich]

It would be interesting to see how this circuit is wired. I have not seen any details on it but the idea seems totally out of the normal operation for LED. Since the stand alone LED requires a pretty specific amount of current flowing through to light, enough to light but not enough to burn out, it seems very unlikely that one led at the breaker could carry nearly enough to provide current to light lots more LED in the fixtures.
In designing LED lighting fixtures for aquarium lighting, one of the primary problems is working out a set of series and parallel paths to get the correct currant to each LED in the array.
Designing a circuit to let a single LED carry even half the load for the fixtures that is usually carried by the breaker seems to be more expensive than I can imagine doing.
New and radical is certainly possible but to put a circuit of that sort on each breaker seems way out there.
Anybody got some info on how this is wired? Any links to the development of the circuit? Something that new would solve several problems in designing LED lighting.

[feiter]

.I had the same problem with the same set of lights...in addition to bath and mbedroom i have a light outside bath door in front of shower that also was dim. I first noticed my problem after adding AGM batteries and a battery monitor with the monitor installed on the wall where all other controls are. The worst thing for me was initially the water pump would not work and when I turned it on the lights would go from dim to out completely. Also had one of two overhead fans out.

In my coach all of the wiring seemed to be on the same 12v circuit labeled "Control Panel" and at one point the fuse in this breaker did blow.

This drove me crazy for 4 weeks. I purchased a new water pump that was not needed as my coach has 2 and when I swapped them they both worked (at times). I replaced the pump switch...nothing. All of this was occurring while unit parked in storage area. Due to virus we decided to take the RV for a visit to my Daughters so we would not have to go into their house and had a bathroom to use. After arrival and hooking up to their water I decided to demonstrate problems to my son in law. Guess what? After driving 40 miles (during which time batteries fully charged) none of the problems existed including non working water pump.

A couple weeks later with unit back in storage and bats discharged problems of dim lights came back but not issue with pump or the ceiling fan.

I did determine it was a low voltage problem using testers but was never able to find out why. I finally took it to Giant RV for service of a few other issues and once again driving about 45 miles I was unable to show the service technician the problems as everything worked.

I have had unit back a few weeks now and everthing seems fine. The dealer fully discharged the batteries after tightening all grounds including the chassis grounds and was not able to duplicate the problems. The dealer could not tell me what the issue was but is fixed (I hope)

So, moral of story...low voltage problems can be caused by loose ground wires so maybe it is your problem also. Hope you have expertise to find the issue as I did not.

[feiter]

Gary...glad you fixed your issue and sorry for my long winded input late in the thread...I didn't read whole until after I posted.

I Have only two wires, both yellow, running to my main cabin switch and I also want to add a dimmer...the dimmer switch I purchased has 3 wires...what did you do with the extra wire? I have nothing metal even close to the switch to run the wire to be the ground.

[Wyatt]

Originally Posted by feiter

Gary...glad you fixed your issue and sorry for my long winded input late in the thread...I didn't read whole until after I posted.

I Have only two wires, both yellow, running to my main cabin switch and I also want to add a dimmer...the dimmer switch I purchased has 3 wires...what did you do with the extra wire? I have nothing metal even close to the switch to run the wire to be the ground.

Hi Bill, sure you do. We have the same RV. The main cabin I tied the ground wire to the main power center under the sink right below.

The hall dimmer and bath I tied together and ran a wire like we did for the Victron down and connected it to a screw on the heater box.

[BobC]

Fuses and breakers aside, in my experience and, in reading numerous power-related posts on this and other forums, mysterious 12V DC problems are most likely related to bad grounds. Mysterious 120V AC problems are most likely related to either a tripped or bad GFCI. Loose screw terminals (especially those into which wires are inserted) are common causes for malfunctioning 12V and 120V devices such as converters, inverters, automatic transfer switches, etc.

Bad internal grounds, failed solder joints and bad capacitors also seem to be the most common reasons for failed electronics. Unfortunately, they're getting harder and harder for even the skilled amateur to repair.

And always look for internal fuses, not just those on your breaker/fuse panels.

[Morich]

Originally Posted by BobC

Fuses and breakers aside, in my experience and, in reading numerous power-related posts on this and other forums, mysterious 12V DC problems are most likely related to bad grounds. Mysterious 120V AC problems are most likely related to either a tripped or bad GFCI. Loose screw terminals (especially those into which wires are inserted) are common causes for malfunctioning 12V and 120V devices such as converters, inverters, automatic transfer switches, etc.

Bad internal grounds, failed solder joints and bad capacitors also seem to be the most common reasons for failed electronics. Unfortunately, they're getting harder and harder for even the skilled amateur to repair.

And always look for internal fuses, not just those on your breaker/fuse panels.

Bob has come pretty close to nailing it on what vexes us most of the time!
And there is good reason for those things to happen. Look at what we do with the RV and how much vibration everything gets! So most any fastener is prone to coming loose, so whether it is the ground connection or some point on the "hot" side, it still begins to get loose and that means a high resistance open where we get less and less voltage going across that impending total open circuit. Low voltage will often cause high current and that does often lead to blown fuses or breakers.
Maybe one way to avoid trouble would be to create a check list of routine tightening of the connections! We might check and tighten the lug nuts but I've never heard of anybody checking the ground wire connection to see if it's tight. Not till we have trouble, anyway!

[BobC]

Thanks, Morich.

[feiter]

So I said close to...I have already decided to splice a piece of wire to switch ground wire and run below as you suggested...thought he might have a better idea.

[Wyatt]

Originally Posted by feiter

So I said close to...I have already decided to splice a piece of wire to switch ground wire and run below as you suggested...thought he might have a better idea.

Only other option is to tie the neutral and ground together at the switch, but, the dimmer function, at least in my dimmer, takes a few minutes to warm up and function as a dimmer.

Just ground it. You’ll be much happier...