LED failed safety alert

[scrubjaysnest]

We had one of the LED lights in the vent fail last night. From the picture you will see three burned resistors and a burn mark by third led from the right. This is what most likely started the failure. My daughter smelled something burning, shut the light off after spotting the smoke. I don't think this was caused by water damage since the LED assembly is sealed in epoxy.
This could have been much worse as closing down the camper doesn't disconnect the shell power from the front shell. With water getting into the switch from the vent the switch could short with the camper closed. If the light than had the failure this one did, major damage could occur. These LEDS were about half the price from the ones carried by the RV stores. The difference is the more expensive ones use 1 resistor and 3 LEDS in series to control the voltage each LED will see. Also they will have a metal tab on one leg of each LED to act as a heat sink. To much heat and the LED shorts, most of the time, which can result in a cascade failure such as happened in my case.

This is just to give everyone a heads up.
I'll do two things, change out to the better LED lights and add another switch to turn off power to the front shell when the bathroom wall is folded down.

Thanks for the heads up, I have converted all of mine to LEDs too, I used the warm white V-LEDs. The switch for the front half is a good idea, I'd like to see where you install it. Thanks!

Thanks for the heads-up. Can you give some specifics as to the source, name, or cost of the lights you bought? Many of us have bought aftermarket lights and would like to know if ours are potentially involved.

[scrubjaysnest]

Originally Posted by Scott O

Thanks for the heads-up. Can you give some specifics as to the source, name, or cost of the lights you bought? Many of us have bought aftermarket lights and would like to know if ours are potentially involved.

I don't have a manufacture name or any kind of brand name. The double dome that failed was bought off ebay for $29.95. The doubles that have the little heat sink on each LED and are not epoxy encapsulated are typically in the $45 to $55 range and have a few less LEDs.

[Bill]

Wow, that is scary! I HATE it when things burn up.

I can think of a couple things that could have been done better by the mfr.

Some of the better LED arrays have a built-in electronic voltage regulator (not a resistor). I think that, in addition to protecting the LEDs from voltage spikes, they go into current-limiting if there is a short - something your LED array obviously did not do.

Heat sink of some kind, as you stated. Otherwise all the heat generated by the array is trapped in the fixture, and can build up to the point of massive failure. An appropriate heat sink would dissipate it into the aluminum inner skin.

A built-in overcurrent or overtemp fuse would be nice. There are some tiny ones, about the size of one of the LEDs. Granted there is not much space to put one in the array you picture.

I know I don't have to tell you, but I'll mention it anyway for others. If you add another cutoff switch, make sure you cut off the lights only. I haven't examined the wiring diagram, but you won't be happy if you also cut off the refrig, for example.

Keep us up to date.

Bill

[Lesherp]

Yikes!

I am using the V-LEDs in my trailer and am wondering if I am at risk for something like this. I am curious if they have any kind of voltage regulator or heat sink. When someone puts in cut off switch I would really like some information on how to do it. It seems rather unlikely that this could even happen as my lights don’t seem to get very warm (I will be checking.). I also have vent covers so it would take some doing for water to get in. That looks scary though.

[scrubjaysnest]

Originally Posted by Bill

........snip

I know I don't have to tell you, but I'll mention it anyway for others. If you add another cutoff switch, make sure you cut off the lights only. I haven't examined the wiring diagram, but you won't be happy if you also cut off the refrig, for example.

Keep us up to date.

Bill

Bill has made an important point here.

Another thing I want to recalculate the load for the front shell fuse, from the factory it is 20 amp. This maybe to high if only the lights are on the front shell power but it will take a very careful check as sometimes other stuff may be wired to that fuse like the refrig in some cases. Ours has a third 20 amp fuse for the refrig, water pump and heater.

[scrubjaysnest]

Originally Posted by Lesherp

Yikes!

............snip...
It seems rather unlikely that this could even happen as my lights don’t seem to get very warm (I will be checking.). I also have vent covers so it would take some doing for water to get in. That looks scary though.

A word of caution here, as a general rule you won't feel much heat.

What happens is the junction temperature of a single LED may get high enough for an internal short to occur..you will most likely not feel it.

This results in a higher current flow through the other LEDs in the string which MAY lead to a cascade failure. It wasn't until the current through the resistors got so high that the resistors started to burn that it becomes noticeable. In my case there were only 4 resistors for 38 LEDs instead of 1 resistor for 3 LEDs. Most of these lights are 36 LEDs and 12 resistors unless they have the regulator that Bill posted. You should be able to remove the lens cover and see how the assembly is made. If the LEDs and resistors are embedded in epoxy than there will not be enough air flow for proper cooling.

Hi All,

When I put in my first make shift 12VDC LED light (not made for auto/RV) and had it fail months later I talked with the tech at the company and got the jest that a 120VAC was still present on the DC side of the fuse box if not filtered out in most RV's.

Since then I replaced the converter with WF8955REP 55 Amp Converter that has a filtered DC side. From best converter web site "* If you look at the back of your existing DC fuse block, positions 1-6 are not filtered from the battery because they do not connect to the battery positive lug. Positions 7-9 are filtered but only if you have a battery installed. With the new fuse block, all nine branch circuits are filtered with or without a battery, to provide clean DC output to ALL of your DC appliances and accessories. "

Just my 2 cents, hope it helps.

Bob

[commodor47]

scrubjaysnest - your photo looks like an LED fixture with the LED wired directly. I recently purchased two LED light bulbs as a replacement for the OEM bulbs in the interior dome light fixtures.

http://www.ledtrailerlights.com/rv/RV-1141.htm

No issues to date -

Dick