LED lighting,12volt household/marine ?

Discussion in 'Electrical Systems' started by grpqueen, Apr 15, 2010.

  1. grpqueen
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    grpqueen Junior Member

    I have been looking at LED lighting for a fit out , marine price tags are considerably more than 12 volt LED household lighting, what is the difference ? I assume that household low voltage 12 volt LED,s are DC.
     
  2. Stumble
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    Stumble Senior Member

    GRP,

    Parts manufacturers seem to do one of two things when they decide to sell Marine products, either they:

    1) Put Marine on the packaging, double the price and thats it OR
    2) Reengineer it from the beginning focusing on corrosion resistance, water proofing, vibration dampaning, then double the price.


    The problem is to tell the difference between the two types of manufacturers, and make sure that you really need the increased price from having something that is actually marinized. The interior lights on a 200' power yacht in a forward cabin with sealed windows where they are unlikely to get exposed to salt water in the first place... well you could probably get away with standard home fixtures. However deck lights on the bow used to light the windlass really need to be marinized.
     
  3. CDK
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    CDK retired engineer

    Don't tell the LEDs they will be installed in a boat and they won't notice the difference.
    I've seen stainless steel household fixtures that will do reasonably well on a boat, especially if the wiring is resin coated to resist humidity.
     
  4. missinginaction
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    missinginaction Senior Member

    I'm glad this is being discussed. CDK, I understand that LED's must be sealed in order to work properly. It wouldn't matter that they were labeled "marine" or not. Besides I see many new LED fixtures being sold at local home improvement stores for next to nothing, compared to the pricy "marine" fixtures. I'm finishing my boat this spring and have a mind to install some of these outdoor type LED's. For the little they cost, if they fail I'm not out much anyway and it's worth a try.

    Regards,

    MIA
     
  5. gonzo
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    gonzo Senior Member

    Cheap LEDs sometimes are of very low quality and last no more than a few hours. Most come from China, where quality control is always questionable. There are about 46 LED farms in China and 4 of them produce lights of good quality. Unless you know where they come from you may be buying garbage. A friend of mine installed lights on his boat and all failed within a month. My LED cost three times more but years later are still good.
     
  6. missinginaction
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    missinginaction Senior Member

    Thanks for the information gonzo. Maybe the trick is to do a mean time before failure test. I'll buy some inexpensive lights, rig them up to a 12 volt power supply and let em run continuously for awhile. If they last a week or two I suppose that they must come from the good supplier. If they fail I'll just bring them back to the store and get my money back.:)

    MIA
     
  7. pistnbroke
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    pistnbroke I try

    I have had good success in potting led units in polyester resin having all the connections inside the resin block and just bringing out the two wires for connection ..just a thought

    All leds are DC unless the unit incorperates a rectifier system ... the ones quoted as 12 or 24v usually have a voltage regulator built in ... the 12v ones just a series resistor
     
  8. CDK
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    CDK retired engineer

    LED quality

    Manufacturing LEDs is a very tedious process, involving many stages, exact temperatures, extreme cleanliness and perfect control of mechanical and chemical properties. And the investments are massive.

    For that reason, only very few companies are able to mass produce them, all of these are Asian, all equally good. All use the same machinery and the same raw materials, so the end product has very little variation.

    Only two factors can influence the product price: selection and marketing strategy. The finished product is tested and selected in brightness classes for a specific application. If LEDs are intended for arrays, you need narrower defined groups than for single applications. Market prices for mainstream LEDs range from approx. 3 to 7 cents.

    When powered according to specifications, LEDs never fail. The colored ones live forever, the white ones have visibly lost brightness after 50 000 hours (approx 6 years). It is the white fluorescent phosphor getting tired, the UV LED underneath then still performs (almost) like new.

    A white LED has a 3V voltage drop and performs best at a current of 20 mA. Less current produces less intensity, more current drastically reduces lifetime: at twice the current, life expectancy is just a few minutes. Even short excess current causes partial damage, changing polarity kills almost instantaneously.
     
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  9. TerryKing
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    TerryKing On The Water SOON

    Hey Pistn, did you encapsulate the entire assembly 100% or did you have the plastic LED packages stick out of the resin? Wondering about the optical result.. Any photo you can put up??

    Thanks for this and many other good ideas. Some of which I've already stolen. As my friend at IBM always said, "It's DUMB if you don't use a good idea, just because it wasn't YOURS!"
     
  10. pistnbroke
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    pistnbroke I try

    yes I did leave the ends of the leds exposed as they were in submersible trailer lights (bought the wrong ones) As yours are not going to be submersed you could just flow some resin over the likley to corrode bits and let the surplus drip off ...
    changed the logo ..as you can see I am having a tough time elsewhere !!!!
     
  11. CDK
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    CDK retired engineer

    Another, quicker way is to use a glue gun to cover the metal parts. The thermoplastic stuff remains flexible so it won't crack.
     
  12. TollyWally
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    TollyWally Senior Member

    My old man used to say with a twinkle in his eye "A good idea doesn't care who has it."

    I've made several experimental self potted switches. All spur of the moment using left over polyester resin from minor repair projects or "marinetex". Never dawned on me to try hot glue. Am quite interested in other folks experiences.
     
  13. missinginaction
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    missinginaction Senior Member

    Back to the LED's folks.

    I see that I can purchase LED's to run on 12 volt systems and I also see products on the market that will work on just about any household fixture that I can imagine. E26 or 27 Edison bases, florescent relacements, halogen replacements all set to run on standard household current.

    I'm all set to begin installing the new wiring in my boat and it occurs to me that I can install LED's designed to run on 12 volts or install standard E26-27 fixtures and wire my lights to run off the inverter instead of off the DC panel.

    I'm starting to think that it might be more practical to run all of my house loads including the interior lights off the inverter and just run the outside loads (nav lights, etc) off the DC panel.

    One question for you electronics experts out there. I'm using a modified sine wave inverter (xantrax xm 1800 watt). Am I going to have any issues with LED's by not running a true sine wave inverter?

    Aside from an inverter failure (I'll always have a flashlight onboard) are there other issues that I've not considered as I think of going 100% AC for my interior house power needs?

    Thanks Folks,

    MIA
     
  14. CDK
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    CDK retired engineer

    Bad idea!

    One good reason to use LED's in the first place is saving energy.
    By first converting 12VDC to 110 AC and then convert that back to the 3VDC an LED needs, you loose that advantage.

    LED's for incandescent bulb replacement use a very inefficient way of conversion because the housing has no space for a more serious circuit and the price must be kept low. As a result, you get less light for your watt, or more watts for the light....
     

  15. TerryKing
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    TerryKing On The Water SOON

    Efficiency is the remaining question.

    IF you want very low power drain with just a few LED lights on late at night, it's better not to run the inverter, which always consumes some power, and it not 100% efficient. Also the Line-Voltage LED lights have an internal "Inverter" back down to low voltage and IT is not 100% either.

    BUT if you're running a larger power boat with lots of other engine-off loads and large house bank batteries, the difference is unimportant.

    AND you'll save size and weight of the wiring to the lamps; the current will be a lot less at 115 or 230 volts...

    BUT the 12 volt lights are intrinsically safe from a human-touching-a-circuit perspective.

    SO: "It's an Engineering Question" - meaning you have to weigh the tradeoffs and the different customers and installers and manufacturers needs...

    But interesting :)
     
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