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Old 01-20-2011, 02:55 AM   #21
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1953 21' Flying Cloud
Encinitas , California
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I have a company that designs and produces LED lighting and controls. I have been involved in this industry since 2002. The quality of LED products on the market is highly variable. Typically the stuff from Asia that opportunistically floods the market is poorly designed with low manufacturing cost being the primary criteria. Whoever you buy from, get a solid warranty (I recommend 3 to 5 years if you can find it, and read the fine print).

The LED lights with integral voltage regulators are probably not dimmable (if that is of interest). For me, it is a show stopper. I prefer the constant voltage (with resistor) type that I can run in parallel and dim with a pulse modulation dimmer. For an RV, this would require a DC-DC converter that holds 12 volts no matter what the input. I would have separate circuits for LED lighting and place the DC-DC converter near my main panel. The dimmer acts on the regulated voltage side of the converter. A 20W DC-DC converter is smaller than a cell phone and costs about $30. Many other sizes are available. I have used some from here: PowerStream Power Supplies and Chargers for OEMs in a Hurry

Thermal management is of paramount importance when implementing LED lighting. LEDs do not radiate their heat forward like an incandescent bulb does. They conduct heat from their base. Aluminum is an excellent conductor of heat. Try to couple the hot spot of the light fixture to interior skins (exterior skins may get too hot in the sun). Also try to get airflow over the hot spots.

And, in case anyone is wondering, I do not produce any lighting for airstreams or other RVs... yet. I am working on my '53 Flying Cloud ground up renovation. When the time comes I will be making my own custom fixtures. There will be no incandescents or fluorescents anywhere on the trailer.

Chris I.
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Old 01-20-2011, 07:35 AM   #22
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1986 25' Sovereign
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Quote:
Originally Posted by dljosephson View Post
Using four white LEDs in series with a resistor might not be the best idea. The bandgap voltage is typically at least 3.2 volts, 4x3.2 is 12.8 which means the light will be very dim once the battery isn't being charged. All of the white LED stuff I've seen uses three in series plus a diode and/or resistor.

The current requirement varies widely. Small 5mm ones will take no more than 20 mA. Some of the bigger ones will take up to an amp, given adequate heatsinking.
Here is a link to the LEDs I bought. They are 350ma on the forward current and 3.2 volt. I did the setup with the LEDs @ 60%. Are you saying i should go higher? I based this on the voltage of 13.8 which is the max I have ever seen on the system with the exception of equalization.
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Old 01-20-2011, 11:16 AM   #23
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ck21084? DealExtreme direct out of china has LED's and drivers for about 30-50% of the ones you linked. Not that I'm pro-import but 95% come from there anyways... Reading the comments of the devices gives some good insight too.
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Old 01-20-2011, 03:44 PM   #24
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1956 22' Flying Cloud
Dallas , Texas
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Quote:
Originally Posted by Star-Man View Post
I have a company that designs and produces LED lighting and controls. I have been involved in this industry since 2002. The quality of LED products on the market is highly variable. Typically the stuff from Asia that opportunistically floods the market is poorly designed with low manufacturing cost being the primary criteria. Whoever you buy from, get a solid warranty (I recommend 3 to 5 years if you can find it, and read the fine print).

The LED lights with integral voltage regulators are probably not dimmable (if that is of interest). For me, it is a show stopper. I prefer the constant voltage (with resistor) type that I can run in parallel and dim with a pulse modulation dimmer. For an RV, this would require a DC-DC converter that holds 12 volts no matter what the input. I would have separate circuits for LED lighting and place the DC-DC converter near my main panel. The dimmer acts on the regulated voltage side of the converter. A 20W DC-DC converter is smaller than a cell phone and costs about $30. Many other sizes are available. I have used some from here: PowerStream Power Supplies and Chargers for OEMs in a Hurry

Thermal management is of paramount importance when implementing LED lighting. LEDs do not radiate their heat forward like an incandescent bulb does. They conduct heat from their base. Aluminum is an excellent conductor of heat. Try to couple the hot spot of the light fixture to interior skins (exterior skins may get too hot in the sun). Also try to get airflow over the hot spots.

And, in case anyone is wondering, I do not produce any lighting for airstreams or other RVs... yet. I am working on my '53 Flying Cloud ground up renovation. When the time comes I will be making my own custom fixtures. There will be no incandescents or fluorescents anywhere on the trailer.

Chris I.
Thanks for your informative message. There is so much to learn about when redoing an Airstream, and it is extremely helpful to learn from others with more knowledge! Hank L.
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Old 01-21-2011, 12:56 AM   #25
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Quote:
Originally Posted by Wabbiteer View Post
Karma to dljosephson for couching technology so understandably.

A vehicles flooded lead-acid battery will appear as an open circuit to the charging source when its fully charged. It starts rejecting acceptance of current around ~14.7V which can allow the alternator (converter) charging circuit to not be limited by the battery load allowing voltage drift to whatever the internal alternator (converter) regulation will allow.
Ouch! I wish that were so! May I send you some exploded batteries that were fed 16 volts for a few days? Fully charged, a lead-acid cell sits at about 2.09 to 2.12 volts (12.6 nominal for a 6-cell battery like we use). It starts drawing a little current at this voltage (lower if it's discharged) and more as the applied voltage is increased, practically without limit. Alternators are typically regulated to try to produce 14.2 to 14.6 volts to make up for some losses in the wiring, and maintain this voltage even without a battery connected. It would be very dangerous to assume that a battery rejects current at any higher voltage.

Quote:
Usual values for newer higher output LEDs is 3 to 3.5V at 300 to 350 milliamps which yields a 1 watt LED (3.5 x .300 =1.05w) so if I string three in series I would need 9 to 10.5V with a resistor to limit the string to 300mA. If they use a generous resistor the light looks good when running off a battery alone but will fry itself eventually when it sees 15V. If they use a stingy resistor the light survives the higher voltage but may appear dim when fed off the battery alone.
That's right -- which is why they use low value resistors, to get the most light out of culled cheap LEDs. On 12 volts they are probably okay, but on typical Univolt or programmed charger voltage of 13.6 to 14.5, not good.
Quote:
Anyway - just some more detail to throw into the fray. Looking for aluminum housings and the wide-voltage range may mean a little better initial design....
Agreed - but there are "aluminum" LED housings out there that are actually plastic, and some I've seen aren't thermally coupled to the LED die at all.

Like anything else, caveat emptor ...
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Old 03-06-2011, 11:54 PM   #26
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San Jose , California
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We just bought a 2011 27 FC. The interior lights are--were--all LED. My wife and I found that they were such intense point sources of light that we started seeing yellow spots after being inside with the ceiling lights on. I posted this inquiry in a different thread and the few that read it had had no adverse experience like we did. I'm wondering if anyone here has had the same experience. So, with apologies for repetition, here's my question: Has anyone else had this problem, and if so how did you fix it? For example, did anyone make some sort of diffuser to lessen the intensity of the LEDs? Also, the factory-installed LED color temperature--blue-white--is too harsh for our taste, but before I replace them with warmer color LEDs, I'd like to know if there's a solution to the intensity problem.

As a stopgap, I replaced all the LED "pancake" light fixtures with 12v halogens. They work great, but the obvious problem we've had is that these lights seem to suck the batteries dry.

I'd appreciate any help

Paul
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Old 03-29-2011, 07:22 PM   #27
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1969 27' Overlander
Snohomish , Washington
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Converted most of the lighting in my boat to LED. The marine lights are designed for the same voltages as an RV would get from an alternator, battery charger, or converter from the shore power.
One thing that can be done is for all lighting circuits put in a Zenor diode rated for 12 VDC. I found that on the boat just one of these lengthened the life of my incandescents and then later my LEDs.
You can now but 12VDC rope lighting that I intend to use like airplane mood lighting by hiding the rope behind a valance.

Here's a mock up shot of the rope lighting behind the stereo cabinet, looks cool with the curvature of the AS end.
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Old 03-29-2011, 08:48 PM   #28
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2007 25' Safari FB SE
Eureka Springs , Arkansas
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I installed 3 LED's from diff sources in the ceiling.
Last weekend was our first trip.
I did learn that they are a better indicator of battery strength than the "Status monitor".
Status monitor showed batteries were good(green). LED's wouldn't light, nor would the furnace @ 37 degrees outside!
After a cold nite, removed batteries, had them checked, both 10+ volts, replaced them and all is OK!

I do think I will replace all lights with LED's as they are much cooler. Color seems much better than earlier ones. There are brights dots, but don't look directly at them.

Bob
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Old 04-18-2011, 05:53 PM   #29
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2004 22' International CCD
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I ordered mine from Dan at LEDs 4, Recreational Vehicles and they've been great to work with. They taught me about the various voltage issues when I did something stupid -- including emailing with me on a weekend. All their lights come with resistors to protect them from excessive current. If you have questions, consult with them.
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