Led lights come on when plugging into shore power

[R1campr]

I keep my micro Minnie plugged into 15amp at home. I unplugged it to Change a puck light that was very dim and wouldn’t turn off. While I was at it, I added a 12v outlet. Red + to the fuse box on a spare fuse spot and neg- to the bus bar for 12v.

When I plugged the power cord back in, I noticed some of the led ceiling puck lights were on, they wouldn’t switch off but slowly went out after about a minute. I never noticed this before, not sure if it’s happened before.

Anybody ever experienced the led’s coming on like this?

I thought maybe my wiring or faulty parts. I double and triple checked the wiring, didn’t find any problems. I first took the new led puck light off, no difference, the lights randomly come on when i plug into shore power. So I unplugged the new 12v outlet, same issue with the lights. So I pull the fuse for the new circuit, same, lights still come on randomly, I unhook the Negative wire from the 12v bus bar, same. Then I removed the positive wire from the fuse box, now everything is the same as before I did anything and when I plug back in or turn on the main breaker, some of the led ceiling lights still come on as before.

Does anyone have any ideas what might be happening here? Or what to check?

Everything works right and battery is charging. The 12v outlet worked when I had it installed. No tripped breakers or blown fusses.

I remember the previous (original) owner mentioned something about these lights randomly coming on.

[Morich]

I would first have to define when and under what conditions the lights are not working correctly. Random is not a very well defined situation!
Do they, in fact, just come on randomly or is there a pattern when they come on? Is it only one or two or all of them just blinking?
One clue, if correct, might be when they come on only when the power cord is plugged in. Since they are 12 VDC lights, they should always be working off the battery, so if they only come on when the cord is plugged and that cord powers the converter charging those batteries is operating, that may be a big clue.

Are you set up with a meter to test voltage and resistance on various parts of the circuit? I might suggest going first to look for good grounding, then with the fuse or breaker for the lights cutoff, a look for stray voltage where there should be none would be a second step.
But first I would have to find out when the problem shows and what had been changed last as it showed.
Open, shorts, grounds, or crosses are common. Random? Not so much!

[R1campr]

They come on when I first plug in to shore power, or turn on the main breaker. Not every time, but more often than not. I think there’s 7 lights, sometimes 1 or 2 or 3, sometimes 4 will come on at the same time, and not the same one/s each time. They don’t blink, they just come on. The only pattern I see is it only happens when I first plug in or turn on the main breaker. And that is not every time.
Yes, they all work correctly with just battery power, and they also work correctly after they shut off within a minute or so of plugging in shore power or turning on the main breaker.

I do have a volt meter, digital. From 12v ground to both battery positive lug, and the charger/converter positive lug, I get 13.8 v with the converter on and 12.8 with the converter off. So the converter is charging the battery. With the ac power off weather it’s unplugged from the house, or turned off at the main breaker in the trailer, and the battery switch turned off, I get anywhere from .4 v to .2 v between ground and the positive lugs after the fuses. I’ll have to check them tomorrow with the fuses pulled. I did test (with 120 power disconnected) for dc voltage from ac neutral and also ac ground to 12v dc positive, I think I got zero reading there. Will have to check again tomorrow.


I’m not clear (forgot) on how to use the volt meter for resistance in ohms, will have to find that out tomorrow as well.

Also, I do have a surge protector on the extension cable, just in case. I did notice though, where the cable plugs into the wall outside, the door for the inlet has a small blue light on when it has power, today that blue light wasn’t on even though the power was hooked up

[R1campr]

I do have a question about stray voltage. The 12v fuse box has a light for each circuit to show when a fuse is blown. How does that light get power if the fuse is blown? If the fuse is blown, the circuit is now open, right? And, will have to check again tomorrow, I think there was some voltage (with battery connected and/or converter on) between 12v ground and the down side of the positive lugs of circuits not being used. I figured there’d be none there

[Morich]

The indicator light would have to be connected in parallel with the normal flow in some way that it gets power from the input side of the breaker rather than output and only comes on after tripping.
I've seen them in catalogs but never dealt with them, so pretty vague!

Trying to sort the main problem is hard because we get so little in the way of help on towables compared to motorized! No drawings to look at what and where.

Just a theory that might be what you are seeing? When you first plug in and the converter begins to work, it is connected pretty directly to the batteries and this "might" be what you are seeing as part of the problem.

When first turned on, the coverter may be starting at a fairly high (13.5? ) voltage as it starts expecting to charge batteries?? But it soon senses the batteries are high enough and backs the output voltage down to what is often called "float voltage". This is one of the good features of newer charging systems as it is able to start with higher voltage to get batteries up sooner but then taper that voltage down as the batteries reach closer to total charge. That lets the charge keep batteries good and fully charged without going overboard and boiling the water off sooner than needed!

Led are not light normal builbs and they are often wired in series. First one from power, through it to go through second and on down the line as a way to control the current through each LED. Lots of different designs to control the current through each LED, so that one failing doesn't overload the others and make them fail at the same time due to an increase from each failing.
Led are not so fussy about the voltage, as long as it is in the correct range but they are more fussy about the current. LED are more on/off if the voltage is right instead of getting dim as voltage gets lower.

This is where the guessing may have to start! If there is something that lets some small voltage get through to the LED circuit and it is there much of the time and then the converter comes on at a high level, it may be enough to trigger the LED to come on. Then as the converter backs down to float voltage, the voltage to the LED is also backed down and they go out?

This gets tricky to locate,s oplease bear with me if I suggest something that is really not practical. I can make suggestions that sound good but take weeks to do, so I'll let you think it over when I make a suggestion. Not all my paper planning ideas are going to work when they get to the real world!!

The 110AC part BEFORE the converter should be isolated pretty completely from the 12DC side where the LED circuit should be. One thing I might want to test would be that it is a problem on the 12VDC side, not something truly weird on the 110AC side.

Is it practical to ask if you can turn off / disconnect the output from the converter going to the batteries? We don't get good info on trailer parts, so no way to look up drawings, etc on the converter but I might "imagine" a lug on the side of the coverter or breaker which might work to disconnect the output side while leaving the 110AC side to be turned on/off as you plug, etc.

Chain of thought is this. If the LED stop coming on when the AC is plugged in but the DC output is not powered, it would seem to say the problem is on the 12VDC coming out???

Guessing and thinking how this could happen gets really iffy. But if there was something like a clamp or even a plastic ty-wrap a bit too tight and pressing the inand out from the switch too tightly together, it might be forming enough of a cross circuit to do wierd things.

Maybe think back to any of the work that you did to anything that might have slightly pressed some wires together tighter than needed?
I've been amazed at how much trouble a little bitty staple can be when it hits a nailhead and comes back up into a cable!

[R1campr]

Morich, thank you for your info on this issue, I appreciate you taking the time to help me.
It’s an odd problem for sure. When the lights do go out, after about a minute or two, they don’t go out all together, and they kind of dim to going out taking about a second, not like flipping a switch.
I left the ac power plugged in and am using the main breaker to turn it all on and off, so I don’t have to go in and out of the camper each time.
I removed the two fuses for the led ceiling puck lights. When I turned on the main breaker the lights on the fuse block lit like the fuses were blown, showing me there is a load on those circuits. Those little lights went out in a minute or so just like the puck lights did. Really odd, as each of those puck lights have a switch on them.
I checked the lugs for those two circuits without the fuses, they were at 13.8 I also checked the voltage on the unused lugs with no load and no fuses. Those were at 9 volts.

I’m not sure I want to disconnect the positive wire coming from the converter, to test the fuse box more, will have to give that some thought.
Next I’ll check where I ran the wires for the 12v outlet, under some wood tunnels in 2 cabinets and in the pass through, just in case I pinched some wires together when screwing the tunnels back down. Not likely, but ya never know.

I know when people change to leds on their vehicles, cars and bikes, they have to put some sort of diode or something before the lights. I’m starting to wonder if that might have something to do with it because none of the other 12v circuits are affected, just the two for the led puck lights.

[Morich]

I've not done the change on cars that needs anything added but in building lights for over fish tank and switching to LED, it is common to add "current limiting resisters".
When having a string of several LED wired without something to limit the current flow, one LEd going bad will stop using current and add that to the rest, so you get into a cascade of ALL the LED going bad if one fails.

Have you looked at the switch and tried to figure why it did not turn the lights off? Not knowing what type switch is there is a pain that leads to guessing but for just a set of LED, it seems like the switch should be a pretty simple one that only has a wire going in and one coming out.
So if that guess is correct (?) and the switch can be gotten out somewhat easy, maybe testing and looking at the switch would prove it good? Just throwing out ideas to use or reject !

Lots of the switches we get in RV are made by Carling and they have a good webiste that often gives really good info on what to expect inside the switch. So if you get the switch out so you can look at it, there may be a drawing on the side or a make and model number. That info can be used to find which lugs do what if it is more than just a simple single contact opening/closing.

If you do get around to looking for Carling info, this is one site that I use at times:
https://www.carlingtech.com/rocker-switches

Any chance the previous folks did some change of lights and they never were exactly right?

[R1campr]

I’m pretty sure the previous owner didn’t change anything, he said he bought it new, right when Covid was taking off, never used it and kept it in a warehouse until I bought it.

These led lights are what I call puck lights, they’re about 4 inches diameter and about a half inch deep. You push on the plastic cover to turn on and off. These have a small spring in the center of the base that pushes out the plastic cover. It looks like the spring just touches the circuit board, must be electronically switched.

I guess I’ll just leave it as it is for now, not really a problem. Now, I know any that come on, will go off after a minute or two. And everything else works like it should. Even the puck lights after they turn off.

Maybe someone will see this that has had the same issue and figured it out.

[Morich]

Sometimes letting the bear sleep is a good idea!
Really sounds like an odd situation but may be common if somebody can come along and explain it!
Sounds like something to wonder about on a cold day but ignore when the weather is good for camping!!

[Ray,IN]

A poor/missing ground somewhere in the RV is allowing one unknown circuit to backfeed the puck light circuit.
No, it's not Easter yet, but the hunt is on anyway to find a poor/missing ground from a hot circuit.

[R1campr]

Ray, how do I go about finding a poor or missing ground? Other than checking the bus bars?
Is it like they say electricity finds the path of least resistance? If there’s a bad ground the voltage will need to go somewhere else? And since these puck lights have such a delicate switch, it goes to them?

When I plug in or flip the main breaker on, I’m guessing there might be a boost of dc voltage from the converter. The ac voltage coming from the garage outlet is 123v. Think I’ll try checking the dc voltage in the first minute of turning on the converter.

[Ray,IN]

Finding a poor ground is a slow tedious process, patience is required. I would begin at the first light fixture if they are daisy-chained ad ohm-out each on/off switch when in the off position..
If they all test OK, I'd then locate the ground wire and test it the same way; continuing until I found the place(s) with high resistance.


Did I mention I hate 12V problems?