Interior LED Fixture has Dimmed

[Last_Train]

Without any preceding symptoms, the under cabinet LED fixture in our galley has suddenly dimmed. Seems to be maybe 2/3 of its original full intensity. I dropped the fixture down from under the cabinet and checked incoming voltage. (I also made sure that the factory made crimps into the wiring harness were secure.)

I'm showing 13.29V at the fixture's contacts when switched on. Interestingly, an identical LED fixture on the other side of our TT measures 13.51V, and it is functioning normally. Both of these readings are when connected to shore power.

So there is a discrepancy between the two incoming voltages with a difference of .21V. The first question is, is that difference the cause of the dimming in that LED?

The other question is why is there a drop in voltage from one side of the trailer to the other?

Thanks for your feedback.

[Last_Train]

MEXICOWANDERER wrote:
Manufacturers push the LED heat limit right to the bitter edge of functionality.

Keep an LED cool and stay under, well under the Imax current limit and a good LED will light for 20 years 24/7.

But RV LED lighting violates these rules. By a lot. So short life is the penalty. SHARP ELECTRONICS for large 10-100 watt chips and CREE for to 5 watt with proper heat sinking and power has given me the best results. Good luck finding CREE LED fixtures.

Pretty consistent with product quality elsewhere in our RVs, but we do get what we pay for for the most part. Appreciate the heads up on the CREE LED fixtures. No urgency about our situation since the thing does put out "some" light, so I've got some time to try to run one of those down.

On another topic, I've spent lots of time in years past driving around northern Mexico - specifically in Tamaulipas State. Stuck around "La Frontera" leading mission trips to waaaay out of the way places in areas no "Gringo" would typically go - but usually no further than 100 miles from the border. Prowled the back streets of Reynosa, loved Rio Bravo (got some good Mexican friends there in whose home I've spent a few nights), and have navigated some back colonias in Matamoros. Love the culture; love the people; love the food!

Just don't know what it would be like to tow our TT down there!

[Last_Train]

DrewE wrote:
.21 V in general would not make that big a difference in the brightness of the LED fixture. If it's a fixture with an active regulator, it should make no difference at all; but even with a cheaper design using e.g. a dropping resistor it should be at most barely noticeable.

You'll have a much larger voltage difference when using battery power alone, at least once the surface charge has dissipated.

It sounds to me more like a fault in the lamp itself.

I'm coming to the same conclusion . . . the product was supplied by a firm in Elkhart called "Perfit RV, Inc.." It's an unsophisticated fixture manufactured in Guangdong, China. This particular model is no longer offered and has even been supplanted by a different one; thankfully the form factor is identical to the older one. So if we order a replacement at least the exterior will look the same.

[Last_Train]

bpounds wrote:
I would first check the individual LED chips in the lamp. You may have lost some. Can you swap it with one from elsewhere in the coach?

A .2 volt difference around a coach isn't unusual, probably means a less than perfect connection somewhere, or how you held the VOM probes. I would be more interested in the voltage measured at the battery and compared to elsewhere in the coach.

Interesting that in recent weeks we experienced a failing LED fixture in our home. Went through all the testing and isolating, etc., and it turned out that a two year old interior LED lighting fixture simply had failed. (Its symptoms were dimming and flickering.) Probably due to failing diodes, I suspect.

In this case in our TT, each and all of the LEDs are illuminated and burning steadily albeit at maybe 2/3 intensity. So first step for me is I will re-crimp a solid connection and then ultimately swap the failing fixture for a known good one. Sort of like I've tested and repaired IT stuff over the years.

Sort of reassuring that a variance in voltage readings around the TT isn't unsettling. The way these things are put together I wouldn't be surprised that there is a less than perfect connection somewhere in the wiring harness. Unfortunately, I cannot trace this circuit very far . . . although the "Sherlock Holmes" in me wants to give it a shot! 😉

[Last_Train]

Lynnmor wrote:

Last Train wrote:


The other question is why is there a drop in voltage from one side of the trailer to the other?

I would check multiple times in case the converter is switching modes or other items are switching on and off.

When the voltage can be repeated, then suspect a poor connection. Also try swapping the fixtures to see if the problem follows the fixture.

Thanks. Good points. As it turns out I had checked the voltages over a two day period, and the variances were consistent. Before swapping with the known good fixture I wanted to hear the wisdom from this forum. I will remove the factory connections and assure that I reattach with a solid crimp.

[MEXICOWANDERER]

Manufacturers push the LED heat limit right to the bitter edge of functionality.

Keep an LED cool and stay under, well under the Imax current limit and a good LED will light for 20 years 24/7.

But RV LED lighting violates these rules. By a lot. So short life is the penalty. SHARP ELECTRONICS for large 10-100 watt chips and CREE for to 5 watt with proper heat sinking and power has given me the best results. Good luck finding CREE LED fixtures.

[DrewE]

.21 V in general would not make that big a difference in the brightness of the LED fixture. If it's a fixture with an active regulator, it should make no difference at all; but even with a cheaper design using e.g. a dropping resistor it should be at most barely noticeable.

You'll have a much larger voltage difference when using battery power alone, at least once the surface charge has dissipated.

It sounds to me more like a fault in the lamp itself.

[bpounds]

I would first check the individual LED chips in the lamp. You may have lost some. Can you swap it with one from elsewhere in the coach?

A .2 volt difference around a coach isn't unusual, probably means a less than perfect connection somewhere, or how you held the VOM probes. I would be more interested in the voltage measured at the battery and compared to elsewhere in the coach.

[Lynnmor]

Last Train wrote:


The other question is why is there a drop in voltage from one side of the trailer to the other?

I would check multiple times in case the converter is switching modes or other items are switching on and off.

When the voltage can be repeated, then suspect a poor connection. Also try swapping the fixtures to see if the problem follows the fixture.