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29-05-2012, 16:59
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#1
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Registered User
Join Date: Oct 2007
Location: virginia
Boat: islandpacket
Posts: 1,967
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LED lights in my bilge pump panel
I am up dating my bilge pump panel as I cant find a new one to cover the old hole. My problem is I changed the lights to led. I thought it would be easy as I went to the auto parts store and bought some 12 volt LED bulbs that fit. Soldered them in and they worked great. Now it is night and I can read a book from the red and green glow from the panel. These LED are way to bright. Question, do I need a lower voltage bulb and how do I deal with a voltage change or do I just reduce the voltage with something.
Many thanks I know it is an easy fix, But I just dont know how.
__________________
That derelict boat was another dream for somebody else, don't let it be your nightmare and a waste of your life.
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29-05-2012, 18:34
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#2
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Registered User
Join Date: Jun 2011
Posts: 132
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Re: LED lights in my bilge pump panel
Not sure it it would work in your case but, we use covers over bulbs in dash panels to reduce glare. As there is no heat almost anything would work that will fit over the "bulb".
Peacetime
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29-05-2012, 19:39
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#3
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Registered User
Join Date: Jan 2011
Location: Caribbean live aboard
Boat: Camper & Nicholson58 Ketch - ROXY Traverse City, Michigan No.668283
Posts: 6,356
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Re: LED lights in my bilge pump panel
you have to be really careful about the lumens rating of any lamp. The automotive bulbs are not especially suitable for the variable voltage of a sailboat either but you can get away with it with care. For large LED's I recommend PWM current regulation. I have used some Radio Shack off-the-shelf LED's for the small lights. Study the packages and look for the voltage, current and lumens output. I fashoned a tiny LED light for my binacle compass this way. You can also install a DC-DC power converter to supply fixed voltage to LED's. Most low cost solutions are also power wasters so do your homework. Here is a source. Murata Power Solutions | DC-DC Converter, AC-DC Power Supply, Digital Panel Meter, Inductor, Common Mode Choke and Pulse Transformer | Murata Power Solutions
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29-05-2012, 20:15
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#4
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Registered User
Join Date: Sep 2009
Location: Halifax Nova Scotia Canada
Boat: Douglas 32
Posts: 30
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Re: LED lights in my bilge pump panel
Pink fingernail polish (don't ask...)
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29-05-2012, 20:19
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#5
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Moderator Emeritus
Join Date: Feb 2011
Location: SF Bay Area
Boat: Islander 34
Posts: 5,486
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Re: LED lights in my bilge pump panel
You might try adding a resistor in series to the led. maybe 300 ohm... ok thats a wag, but a resistor for a normal led would work... it would not work with the high output ones, btw
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29-05-2012, 23:07
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#6
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Moderator
Join Date: Jul 2007
Boat: Bestevaer.
Posts: 14,678
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Re: LED lights in my bilge pump panel
Quote:
Originally Posted by sailorchic34
You might try adding a resistor in series to the led. maybe 300 ohm... ok thats a wag, but a resistor for a normal led would work... it would not work with the high output ones, btw
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I agree a resistor in series.
Experiment with the value to find the brightness you want. More resistance will make the LED duller.
Ordinary 1/4 w resistors should be fine. The easiest way would be to buy a bag of resistors from an electronics shop.
An alternative would be to de-solder resistors from any junk electronic components and give them a try. You will not damage anything. There is no need to even read the value, just try them untill you get desired brightness. Some will make the LED very dull and some will have little effect, but you should be able to find something that is just what you want.
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30-05-2012, 05:03
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#7
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Nearly an old salt
Join Date: Jun 2009
Location: Lefkas Marina ,Greece
Boat: Bavaria 36
Posts: 22,801
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Re: LED lights in my bilge pump panel
This not an uncommon problem, many indicator LEDs are too bright in complete darkness yet hardly can be seen in daylight. Theres no easy solution outside auto dimming try the resistor idea to see if you can get a compromise.
PS: its not clear what exact type you bought so if there are higher power LED the 1/4 resistors might be a wee bit hot!If its a wedge or bayonet indicator LED these draw about 15 mA. so these should be OK.
__________________
Interested in smart boat technology, networking and all things tech
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30-05-2012, 06:46
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#8
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Registered User
Join Date: Feb 2011
Location: Boise, ID
Boat: Trawler
Posts: 40
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Unfortunately LEDs don't work like regular bulbs so just dropping voltage with a resistor isn't going to work. I think the nail polish trick is your best bet (unless you want to get into making a pwm circuit as was previously mentioned...pwm turns the led on & off really fast making it appear dim)
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30-05-2012, 07:01
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#9
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Moderator
Join Date: Jul 2007
Boat: Bestevaer.
Posts: 14,678
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Re: LED lights in my bilge pump panel
Quote:
Originally Posted by FloatyThing
Unfortunately LEDs don't work like regular bulbs so just dropping voltage with a resistor isn't going to work. I think the nail polish trick is your best bet (unless you want to get into making a pwm circuit as was previously mentioned...pwm turns the led on & off really fast making it appear dim)
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Your probably thinking of a LED fitting that is already regulated ( generally by PWM). The circuitry for these fitting will maintain a constant brightness over a range of voltages, so dropping the voltage does not effect the current.
Indicator LEDs Do not have this sort of complicated circuitry, they have a simple dropping resistor. (at least i have never seen them wired any other way) Adding more resistance in series reduces the current flowing through the LED and will reduce the brightness.
It is very easy to try and will do no harm even if the led has more sophisticated regulation and the chance of this is very remote.
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01-06-2012, 08:43
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#10
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Registered User
Join Date: Oct 2007
Location: virginia
Boat: islandpacket
Posts: 1,967
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Re: LED lights in my bilge pump panel
Many thanks for the suggestions. I will try the reistors then the fingernail polish.
__________________
That derelict boat was another dream for somebody else, don't let it be your nightmare and a waste of your life.
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07-06-2012, 06:42
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#11
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Registered User
Join Date: Jun 2012
Location: Texas
Boat: Hinckley Bermuda 40
Posts: 845
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Re: LED lights in my bilge pump panel
I recently added LED's to my breaker panel. I got these at my local electronics parts house. 1/4 watt resistors of the appropriate value were included. Be sure you get 12 v. LED's, because AC will not work. Various colors are available, as well as different diamater mounting options- I got itty bitty ones- 3/16 snap in. Be sure you use some kind of heat sink /absorber (alligator clip, etc. ) when you solder these in, because LED's can fry from soldering heat.
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08-06-2012, 19:19
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#13
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֍֎֍֎֍֎֍֎֍֎
Join Date: Apr 2006
Posts: 15,136
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Re: LED lights in my bilge pump panel
Santa, if you have a multimeter you can probably do some easy math instead of just throwing odd resistors at it.
Use the ammeter function, see how much power one LED is drawing. I'll take a rash guess it is 40mA. Now disconnect one LED and measure the resistance through it. Reverse the meter leads and try again if it says infinite. You can plug those numbers into some LED resistance calculators to find out what is going on and what voltage drop they are generating in the "bulb" assembly.
If the LEDs are drawing 40mA now, and you reduce that to 20mA, they'll probably still be visible in daylight but dimmer at night. Resistors are probably 5/$2.50 at Radio Shack and you could certainly try just throwing another 200-400 ohms on one to see if that dims it enough, but if you can give it another 48 hours and run some numbers...
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08-06-2012, 21:35
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#14
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Registered User
Join Date: May 2012
Posts: 23
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The bottom end for brightness of high brightness LED's is at a forward current of about 10mA. The math is (VBatt-VFwdLED)/IFwd=R. Figure 12.4V for your battery bank (VBatt), VFwdLED is typically 1.9V, and IFwd (as mentioned above) is 10mA. So... (12.4V-1.9V)/10mA=1050 ohms, or in practice a 1k ohm resistor (Brown,Black,Red). This will likely do the job.
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08-06-2012, 23:43
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#15
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Moderator
Join Date: Jul 2007
Boat: Bestevaer.
Posts: 14,678
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Re: LED lights in my bilge pump panel
Quote:
Originally Posted by ExRonin
The bottom end for brightness of high brightness LED's is at a forward current of about 10mA. The math is (VBatt-VFwdLED)/IFwd=R. Figure 12.4V for your battery bank (VBatt), VFwdLED is typically 1.9V, and IFwd (as mentioned above) is 10mA. So... (12.4V-1.9V)/10mA=1050 ohms, or in practice a 1k ohm resistor (Brown,Black,Red). This will likely do the job.
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This is the total resistance for a 10mA current. There is already a resistor in the circuit dropping the forward current (to about 20mA would be my guess). The resistor that is needs to be added in series to reduce the brightness will be much less.
I would not recommend replacing the existing resistor. That is unessasary and you need to careful soldering the LED itself. Just add another resistor ( or multiple resistors if you like ) in series.
The trouble with the calculated value is that difficult to estimate what the forward current will be to give the correct brightness.
I still think a practical, try a resistor and see, is the best approach.
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