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Old 07-29-2017, 03:47 AM   #1
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LED Caution

Hoping my picture is attached, lol. I'm an incurable lurker of the forum but wanted to share our discovery this week. We have a 2016 ultra lite, and my husband accidentally left the front LED lights on over night. I was alarmed to find a scorched area next to the LED strip. We don't typically have those on, but had turned them on for a celebration. They will be permanently disconnected today....
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Old 07-29-2017, 04:32 AM   #2
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I'm certainly no electrician but I would suspect "arcing" due to a not-so-well-connected set of wires. LEDs should not generate enough heat to do this, but if there's a short where wires aren't connected the electricity can arc and cause a great deal of heat.

If it's under warranty, I'd get it back in to the dealer for them to remedy this.
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Old 07-29-2017, 05:00 AM   #3
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Originally Posted by rjshiflet View Post
I'm certainly no electrician but I would suspect "arcing" due to a not-so-well-connected set of wires. LEDs should not generate enough heat to do this, but if there's a short where wires aren't connected the electricity can arc and cause a great deal of heat.

If it's under warranty, I'd get it back in to the dealer for them to remedy this.
Agree 100%

I leave ours on all night routinely for security reasons unless there is someone close who would be bothered.
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Old 07-29-2017, 05:34 AM   #4
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LEDs should not generate enough heat to do this
The LEDs themselves don't, but there is a DC-DC converter to lower voltages to whatever the LEDs use (3.3V or even less). The DC-DC converter can get hot, even more so when running outside of its specs which is not uncommon.
That's a frequent problem with cheap LED replacement lights as well, the 10 pack for $15 on Amazon kind. You want a DC-DC converter that can deal with the fluctuating input voltages in an RV. E.g. the T15 LED lights I have claim 8-30V DC.
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Old 07-29-2017, 05:54 AM   #5
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Question for "The German" do the LED lights that are used by F/R in the Rockwood/Flagstaff units have "DC- DC converter in the "8-30V" range and is this the Proper Range and also How do we tell if our LEDs are Correct? Can we tell by just Looking? Youroo!!
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Old 07-29-2017, 02:12 PM   #6
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Question for "The German" do the LED lights that are used by F/R in the Rockwood/Flagstaff units have "DC- DC converter in the "8-30V" range and is this the Proper Range and also How do we tell if our LEDs are Correct? Can we tell by just Looking?
First off, apologies I had a brainfart last night when I wrote DC-DC converter - voltage regulator is what I meant.

Sorry I don't know what LEDs FR uses (my trailer did not come with LED lights) and unfortunately the components are typically not visible without breaking the fixture apart. I'd think FR just goes to their suppliers and the actual manufacturer might change from time to time.

The super cheap LED lights consist of just LEDs and resistors. These have a narrow operating range and can start to flicker/turn off as battery voltage drops.They also only work when the polarity is correct (might need turned around to work). The polarity issue is an easy way to spot these.

RV specific LED bulbs typically operate from 8-16V or 8-30V, the latter working in 24V systems (boats AFAIK). Obviously 8-16V is sufficient for trailers, it covers the typical range of battery operation.
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Old 07-29-2017, 02:31 PM   #7
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X2 on the cheap LED voltage regulators. In addition to many of them not being able to dissipate the heat they generate, they generate considerable RF noise which can make using your radio and TV difficult. The reason you can but a pack of 10 LED modules on ebay for $10 and a single brand name module for $13 is the poor quality drive components.
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Old 07-29-2017, 03:08 PM   #8
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The super cheap LED lights consist of just LEDs and resistors. These have a narrow operating range and can start to flicker/turn off as battery voltage drops.They also only work when the polarity is correct (might need turned around to work). The polarity issue is an easy way to spot these.
While I agree with much of what you said, I think you have the resistor-circuit a little off. Typically in a resistor led drive circuit, for 12 volt operation, the LEDs are hooked in series (three? LEDs in series) and then a resistor is added, also in series. As the LEDs each drop about 3.3+/- volts, the resistor is dropping the remaining voltage to the supply - e.g., in the three in series example, at 12.5 volts battery, the LEDs drop about 10 volts and the resistor about 2.5 volts. The circuit is actually very well behaved with dropping or rising voltage - as the voltage increases, the voltage drop on the resistor increases, increasing the current though the LEDs, and increasing the light output. The LEDs will continue to light (but will get dimmer) as voltage decreases until the voltage drops below the "threshold " voltage for the LEDs (about 9 volts in the three LED in series example). No flickering on and off. The circuit is inherently polarity sensitive, as you state - but some resistor drive LEDs use a diode bridge to eliminate polarity sensitivity. Resistor LED drive circuits are RF noise free and are easy to dim, by adding an external resistor. Unfortunately, some low end resistor LEDs use underrated resistors, which fail prematurely (I find this more of an issue than the brightness variation with voltage).

An electronic drive circuit also may or may not be polarity sensitive, and is more likely to "flicker on and off" with low voltage. The electronic driver tries to maintain constant output current to the LEDs over a range of voltages, keeping light output constant when the input voltage changes - e.g., same brightness when boondocking on battery power at 12.3 volts as when plugged in or on generator with the converter charging the batteries at 13+ volts. As the electronic drive circuits often use high frequency oscillators to accomplish their task, they are the source of the RF interference issues some have reported (TV or radio noise or loss of signal when the LED lights are turned on, dimmed, etc.).

Personally, I have had excellent results with resistor style retrofit LEDs in our Solera. They are dimmer when we are on battery power, but are sufficiently bright that I have several on double throw switches with a dimming resistor in one position - can just throw the switch to the bright (no added resistor) position if more light is desired. I have encountered some issues with early failures - stopped using that brand. Other brands have been excellent- no failures in five years and over 300 nights camped. Zero RF interference.

FYI
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Old 07-29-2017, 03:55 PM   #9
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Thanks, your description makes sense, I may have gotten that backwards. I remembered when researching RV LED lights some people were complaining about LEDs starting to flicker/fail after a short time. It probably had a different cause.
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Old 07-29-2017, 04:08 PM   #10
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Underrated resistors can fail prematurely and can cause flickering when they fail. May be what was reported.
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