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Old 01-19-2011, 01:53 AM   #1
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Report on LED int light replacments

We have been replacing many of the lights in our 1983 Airstream motorhome with LEDs. We often boondock and keeping power drain to a minimum makes positioning the unit for max sun (for the solar panels) a little less critical. Initial results were quite positive until the LEDs started dying after a couple of months. I started opening things up and figured out what was going on, thought people would be interested.

White LEDs on the market today are offspring of the original Nichia design, which uses an ultraviolet or blue light emitting diode that excites a disk of phosphor, much the way a fluorescent light uses a UV-emitting vapor to excite a phosphor on the inside of the glass. So the first problem is the color of the light -- the most efficient ones are the "cool white" phosphors, just like with fluorescent tubes at home. These are really too blue or green for my taste, so be on the lookout for "warm white" ones, typically the best we have found are rated at 3000 degrees K. The 2700 are too yellow and the 4300 are too blue. Some of the 3000 ones are quite nice, similar to the newest compact fluorescent lights.

These LEDs operate on about 3.4 volts DC and have a maximum current that depends on the chips' ability to get rid of heat. Typically three LEDs are connected in series, requiring 10.2 volts. Another diode or two and/or a resistor are used to set the current to proper value with 12 volts applied. My first clue that something might be fishy was a note packed with some of the LEDs saying they shouldn't be used all the time, and shouldn't be used when they would get hot. Okay, 50,000 hour lifetime but I can't accidentally leave them on during the day?! Sure enough, I left one in a reading light on and came back a couple weeks later to find it dimmed out nearly completely. Same thing for a panel of them on the step light over the door.

Turns out most of the cheap lights are built for 12 volts -- but if your trailer or moho is plugged in, the "12 volt" line is something between 13.5 and 14.5 depending on how aggressive your charger is. This was causing the LEDs to heat up and fail. One of the usually reliable Airstream dealers sold me six of these in various configurations, all of which have failed or gotten significantly dim. I opened one up and found several strings of 3 LEDs each connected in parallel, sharing a single dropping resistor. So if one string of LEDs burns out, the others will soon follow as now the dropping resistor allows more current through the remaining LEDs. The panels at least had a separate resistor for each group of 3 LEDs so a failed LED wouldn't cause the whole array to die.

If you get LEDs with simple resistor current limiters, be sure they are rated for 14 volts rather than 12. Most of the LED clearance lights are in this category. Red and amber LEDs don't use a phosphor though and are less sensitive to over-current conditions.

Other vendors offer LED conversion bulbs rated for "10 to 30 volts." They are a few dollars more but well worth it -- inside each light or panel is an LED driver circuit that regulates the current to the correct value regardless of input voltage. This is the only kind you should buy. As the voltage is increased, the current actually goes down as the regulator goes to work. The only downside of these units is that the regulator switches at 100-400 kHz, which could cause fairly nasty noise if you're listening to AM or shortwave radio, probably CB too. No problem for FM, cell phone or any kind of satellite because the frequency is sufficiently high but be warned that lower frequencies might be affected.

We have several of the "10 to 30 volt" or "current regulator" type LED arrays installed now and they're working nicely, at roughly 1/10 the current consumption of a similar brightness incandescent. Any surviving "12 volt" types have had the resistor changed to a higher value to permit their use on 14 volts average -- a little less bright but not going to fail in a few weeks of use.
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Old 01-19-2011, 02:30 AM   #2
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Sorry I missed the extensive threads on this topic elsewhere in the forum... looks like the same sort of experiences.
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Old 01-19-2011, 03:55 AM   #3
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TY for posting... we're going to have to re-do the interior lights & want to go LED as we plan to do the solar thing as well asap (a year or so but this is GREAT info & will help us down the road w/RAQUEL (our '68 22' Safari) 1st trip is coming up... nothing fancy... just getting her across country
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Old 01-19-2011, 05:55 AM   #4
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Any ideas on where to purchase the 10-30 volt LED's? Looks like LEDs 4, Recreational Vehicles sells the kind that can't get over 80F? Since I live in any area where our nightime lows are often around or over 80F, I really need to get the right product it seems... Thanks for posting this, wouldn't have known otherwise.
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Old 01-19-2011, 08:53 AM   #5
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Fulltimin, where did you purchase the ones that your were happy with? I have purchased ones from Outdoor Mart and the Airstream store (they seem like the same bulbs) and they have worked fine so far.
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Old 01-19-2011, 09:06 AM   #6
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Quote:
Originally Posted by dljosephson View Post
We have been replacing many of the lights in our 1983 Airstream motorhome with LEDs. We often boondock and keeping power drain to a minimum makes positioning the unit for max sun (for the solar panels) a little less critical. Initial results were quite positive until the LEDs started dying after a couple of months. I started opening things up and figured out what was going on, thought people would be interested.

White LEDs on the market today are offspring of the original Nichia design, which uses an ultraviolet or blue light emitting diode that excites a disk of phosphor, much the way a fluorescent light uses a UV-emitting vapor to excite a phosphor on the inside of the glass. So the first problem is the color of the light -- the most efficient ones are the "cool white" phosphors, just like with fluorescent tubes at home. These are really too blue or green for my taste, so be on the lookout for "warm white" ones, typically the best we have found are rated at 3000 degrees K. The 2700 are too yellow and the 4300 are too blue. Some of the 3000 ones are quite nice, similar to the newest compact fluorescent lights.

These LEDs operate on about 3.4 volts DC and have a maximum current that depends on the chips' ability to get rid of heat. Typically three LEDs are connected in series, requiring 10.2 volts. Another diode or two and/or a resistor are used to set the current to proper value with 12 volts applied. My first clue that something might be fishy was a note packed with some of the LEDs saying they shouldn't be used all the time, and shouldn't be used when they would get hot. Okay, 50,000 hour lifetime but I can't accidentally leave them on during the day?! Sure enough, I left one in a reading light on and came back a couple weeks later to find it dimmed out nearly completely. Same thing for a panel of them on the step light over the door.

Turns out most of the cheap lights are built for 12 volts -- but if your trailer or moho is plugged in, the "12 volt" line is something between 13.5 and 14.5 depending on how aggressive your charger is. This was causing the LEDs to heat up and fail. One of the usually reliable Airstream dealers sold me six of these in various configurations, all of which have failed or gotten significantly dim. I opened one up and found several strings of 3 LEDs each connected in parallel, sharing a single dropping resistor. So if one string of LEDs burns out, the others will soon follow as now the dropping resistor allows more current through the remaining LEDs. The panels at least had a separate resistor for each group of 3 LEDs so a failed LED wouldn't cause the whole array to die.

If you get LEDs with simple resistor current limiters, be sure they are rated for 14 volts rather than 12. Most of the LED clearance lights are in this category. Red and amber LEDs don't use a phosphor though and are less sensitive to over-current conditions.

Other vendors offer LED conversion bulbs rated for "10 to 30 volts." They are a few dollars more but well worth it -- inside each light or panel is an LED driver circuit that regulates the current to the correct value regardless of input voltage. This is the only kind you should buy. As the voltage is increased, the current actually goes down as the regulator goes to work. The only downside of these units is that the regulator switches at 100-400 kHz, which could cause fairly nasty noise if you're listening to AM or shortwave radio, probably CB too. No problem for FM, cell phone or any kind of satellite because the frequency is sufficiently high but be warned that lower frequencies might be affected.

We have several of the "10 to 30 volt" or "current regulator" type LED arrays installed now and they're working nicely, at roughly 1/10 the current consumption of a similar brightness incandescent. Any surviving "12 volt" types have had the resistor changed to a higher value to permit their use on 14 volts average -- a little less bright but not going to fail in a few weeks of use.
Good point about the importance of ensuring LED's are ok for a voltage higher than 12v.

I have installed LED's in the reading lights at the front and rear of our trailer and they seem to work fine.

So then, as a next step, I ordered some T-10 ones to use in the three bulb fixture over our dinette.

They looked good when I put them in and I was happy.

But then, within a few hours use, a couple became quite dim. I removed the bulbs to examine them and as I did so, about half of the little LED "squares" just dropped off the bulbs - solder melted I am guessing.

The three $15 bulbs are garbage and I'm back to the regular T-10 automotive style bulbs.

I should maybe have sent them back, but I already had a bit of a hassle with the supplier as originally he sent me cool white when I ordered warm white.

As well, I sort of guessed it might have been a voltage problem and figured I would just get into an arguement with the supplier so I wrote it off
to experience.

I still like the idea of the LED's and may try again one day but if I do I will ensure this time that they are rated to be ok on at least up to 14V or so,

Strangely I have never had a problem with the ones I installed on the reading lights, but they are a quite different design.

Appreciate it if someone can post contact info for a vendor who can provide the superior design of bulb.



Brian.
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Old 01-19-2011, 10:03 AM   #7
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I replaced all my interior lighting a couple of years ago with leds purchased from superbrightleds.com and have been completely satisfied. There have been no failures and their intensity is the same as when they were installed. All were ordered as warm white.
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Old 01-19-2011, 10:04 AM   #8
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Great information here.

I am planning on making my own LED panels using 4 ~ 1 watt LED's in series with a 3.3 ohm resistor. This will give me a voltage tolerance of 13.8 volts. I think 4 LED's should be plenty bright for the outside door light. I might also install some on the inside as well.

The cost of this project is/was $45 after shipping. I will use a piece of 1/4" Aluminum as a heat sink and will secure it with thermal paste/glue. I will report back with pictures once this is done.
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Old 01-19-2011, 10:07 AM   #9
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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.

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.

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....
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Old 01-19-2011, 10:49 AM   #10
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I have been extremely happy with my fluorescent lights. For general, diffuse lighting, they are as efficient in useful light per watt as LEDs. Since I replaced the tubes with higher-quality ones the light has been warm and the color rendition good.
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Old 01-19-2011, 10:55 AM   #11
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I have been extremely happy with my fluorescent lights. For general, diffuse lighting, they are as efficient in useful light per watt as LEDs. Since I replaced the tubes with higher-quality ones the light has been warm and the color rendition good.
Jammer,

My rig did not come with fluorescent lights. Could you post a few pics of what the look like? Also do you have the over head door light or the scare light? If over head what comes in this?
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Old 01-19-2011, 11:04 AM   #12
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This is sure some great discussion. I have been contemplating going all LED on my renovation and am now questioning if this is such a good idea...
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Old 01-19-2011, 11:20 AM   #13
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We installed LED's (from Airstream) through out our Safari. Also installed them in my hunting trailer (sob). All of the lights are doing well and so far very happy. We do a lot of boondocking in both our AS and the hunting trailer and really like slow bat. drain.
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Old 01-19-2011, 11:36 AM   #14
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One point made by dljosephson i think bears repeating. The fluorescent and LED phosphors are similar and produce a similar quality of light. Almost all of the original equipment fluorescent fixtures use a low end lamp with poor color rendering. This lamp can be replaced with a superior lamp.

I have the 10-30 volt LED and have been happy with them I'd love to test them sometime to see how steady the light output holds through different input voltages. They appear more stable than the incandescent lamps during low voltage.
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