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ContinuousWave: Small Boat Electrical
Nav Light ON with the switch OFF
|Author||Topic: Nav Light ON with the switch OFF|
posted 11-08-2010 02:01 PM ET (US)
I was headed to the airport very early one morning last week and happened to glance at my Outrage 22 resting on its trailer in the back yard. The red running light appeared to be on. At first, I thought it might be reflecting light from my truck, but I headed over to take a closer look. Indeed, the red light was burning. So I climbed in the boat to turn the switch off. But the switch was already off, so I turned it on. The light got brighter, but when I turned it back off, the red lamp continued to glow. When I turned on the switch, the green light came on, but was noticeably dimmer. All of this was after a pretty big thundershower, so everything was wet. By this time, I was out of time, so I dashed for the airport. My wife turned the battery switch off and took care of the immediate problem, but my question now is what caused the red light to come on in the first place? I have a very simple wiring set-up: Batteries to 1-2-Both-off Perko switch, Perko switch to fuse block, fuse block to bank of six marine switches, switches out to different loads. (Red and Green running lights wired together, All-around white light, under gunnel lighting, bait well, (2) spares). My running lights are Attwood LED units that have performed flawlessly to this point. Where do you think I am getting enough current to power an LED light with the switch "off"?
posted 11-08-2010 11:59 PM ET (US)
Check the switch, could have a wet dirty situation allowing some power across the open switch, easy way to check is switch the wires to one of the other switches for a test. I assum ethe switches are protected from water and that the only things on the nav. light switch are the two nav. lights.....jack
posted 11-09-2010 07:38 AM ET (US)
Is the switch that controls the navigation lamps wired in the positive lead?
posted 11-09-2010 08:16 AM ET (US)
Also, the mystery here is why only one of the lamps is illuminated. I assume that the two sidelight lamps are wired to the same switch pole. It is hard to construct a situation with the switch where it only provides power to one of the connected lamps.
posted 11-09-2010 10:35 PM ET (US)
You obviously have a high resistance short (water, crud, et al.) around the switch - to cause the light to be lit. The hooker is the dimmness of the green nav light when you flip the switch - which says that there is further resistance - to ground - in that circuit as well. Consider giving your existing switch the "merry ride". --- Jerry Townsend
posted 11-10-2010 07:55 PM ET (US)
yes, the switch interrupts the positive lead. All neutral (black) leads terminate in a ground bus. This weekend I plan on disassembling the switch bank, thoroughly cleaning, coating with corrosion X and re-installing. I will also check the terminations on the the green nav ligth--perhaps there is some oxidation built up creating resistance. I will let you know what I find.
posted 11-15-2010 08:52 PM ET (US)
Red light on, green light off can be explained by LEDs. The
two side lamps have LEDs with a different forward voltage drop.
Let's say the red is 8V and the green is 10V. That means the
red will come on at 8V and the green at 10V. AND there's
a high resistance short at the switch. The short will flow
enough current to turn on the red, which will pull the voltage
down to 8V. 8V is less than 10V, so the green doesn't turn on.
At full voltage, the lights have a current limiter chip that
LEDs can cause crazy effects. I replaced all the bulbs in
posted 11-15-2010 10:13 PM ET (US)
I think Chuck's suggestion of different forward voltage drop in LED lamps of different color is only plausible if there are a different number of diodes in the internal wiring of the lamp. I don't recall that different color LED's had different voltage drops for individual diodes.
posted 11-16-2010 12:15 AM ET (US)
I pulled up the data sheets for a random LED (Lumileds Rebel).
Green has a forward voltage of 2.55V, red is 2.31V.
posted 11-16-2010 05:27 PM ET (US)
Well, as the old saying goes, you learn something every day. I did not realize that there was such a range of forward voltage drop among the various types of colored LED's. There is a good Wikipedia article on this topic:
However, what has not been demonstrated is that in the boat in question the lamps use colored LEDs. The lamps could use a standard white-light LED and then use a colored lens to create the colored light. It may very well be that this is indeed the technique, because the light emitted by a navigation lamp has to conform to a certain color spectrum to meet the technical requirements of a proper navigation lamp. The red light from a red LED or the green light from a green LED might not fall into the permitted color spectrum.
posted 11-16-2010 05:28 PM ET (US)
Oops--here it the link I meant to include above:
posted 11-16-2010 05:34 PM ET (US)
The chromaticity of navigation lamps is specified in:
§ 84.13 Color specification of lights
but the format of the specification is not in wavelength of light but rather in units defined by the International Commission on Illumination (CIE). According the Wikipedia article the wavelength of emitted light from green and red is
RED = 610 to 760 nm
GREEN = 500 to 570
If we have any physicists reading who can convert wavelength of light to the International Commission on Illumination (CIE)specification, we would appreciate a demonstration in this case. Thanks in advance.
posted 11-16-2010 05:44 PM ET (US)
Well, here is a start. I found this chart:
If we look at the bounding box for "G" or green LEDs, it looks like the boundaries are approximately
Y = 0.64 to 0.75
posted 11-16-2010 05:58 PM ET (US)
White LEDs are more expensive than colored LEDs. It would
be dumb to use a more expensive LED, AND have to use more
LEDs because the lens attenuates the other colors.
posted 11-16-2010 10:21 PM ET (US)
Chuck--Your reasoning is reasonable, but it does not demonstrate conclusively that the lamps in question have specific colored LEDs in them.
Now I was giving some more though to the "white" light from a white LED. A white LED makes is light by a combination of light from red, blue, and green LEDs mixed together. Even if you put a color filter in the lamp to change the light to the proper color or chromaticity, if the "white" LED did not emit any light in that spectrum you might not get much light output.
We need padre' to disassemble the lamps on his boat to see if they LEDs inside them are colored LEDs or white LEDs. That is about the only way to resolve the question.
posted 11-17-2010 09:24 AM ET (US)
That's NOT how white LEDs work. The actual LED is a deep blue
(close to UV) LED that excites a white phosphor.
And even if they worked the way you say, you would still be
posted 11-17-2010 02:06 PM ET (US)
Chuck--I haven't made a study of modern LED lamps, but I rely on Wikipedia, which says:
"There are two primary ways of producing high intensity white-light using LEDs. One is to use individual LEDs that emit three primary colors—red, green, and blue—and then mix all the colors to form white light."
If you have expert knowledge about how LEDs make white light, you perhaps might want to become the editor of the Wikipedia article and emend it so it stops passing off this bad advice to people who read it.
posted 11-17-2010 02:25 PM ET (US)
To get back to my question:
Do the typical "red" and "green" LED lamps emit light which satisfies the technical requirements for red and green sidelights?
posted 11-17-2010 03:50 PM ET (US)
From the same Wikipedia article:
"However, the phosphor method is still the most popular method for making high intensity white LEDs. The design and production of a light source or light fixture using a monochrome emitter with phosphor conversion is simpler and cheaper than a complex RGB system, and the majority of high intensity white LEDs presently on the market are manufactured using phosphor light conversion."
posted 11-18-2010 03:09 PM ET (US)
Navigation lamps are a special case of "colored light." I don't believe that manufacture of navigation lamps using LED light sources would necessarily have to be bound by the market trend toward a particular technique. It very well could be that 99-percent of LED lighting used a certain type of LED and technique, but in a situation where colored light of a specific chromaticity was required, an alternative technique was used to create it.
On a marginally related note, the interior of my car has indirect lighting for ambiance that can be selected from a variety of colors. I suspect that the light sources are red, blue, and green (and perhaps more) LED's which are switched on in various combinations to create the different colors, including white. That is a case of white light being made with LEDs of various colors, and in rather high volume of production.
posted 11-18-2010 07:02 PM ET (US)
The LED's are indeed red and green, not white with a color filter. To Chuck's point, LED's are most efficient as a monchromatic source and navigation lamps (and traffic signals, exit signs, etc.) are monchromatic applications, so there is no good reason to take bluish light, transform it with phosphor to full spectrum and then filter out 90% of the light which is now the wrong color.
I cleaned everything up and the problem disappeared, but I am not sure that the problem was not already gone due to the fact that we have not had rain for several weeks.
Anyway, thanks for the advice and lively discussion.
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