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Old 03-17-2013, 11:49 PM   #41
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Originally Posted by skidgear View Post
In an earlier post, rwidman commented that a controller for the whole boat would not be practical because as you turned lights on and off, the current requirements would change. I was trying to understand why that would be the case if the dc-dc power converter was sized big enough to handle all the lights in the circuit, and all the bulbs in the circuit were matched to the characteristics of the converter.
I don't think that would make any difference. As long as the total amperage of the fixtures did not exceed the rating of the controller, you would be fine. The only caution I could find is the the output v. must remain above the input v. by some specified amount. The controllers I found were cheap enough to put one in each fixture (see post above) if you wanted to.
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Old 03-18-2013, 06:19 AM   #42
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I think you guys are making too much of a non issue....
I have ran LED's in two boats and a RV so far.. and have not had any fail. I had one D.O.A. but that doesn't count . I think the bigger issue with LED's is to make sure they do not cause too much interference with the other electronics. I had LED's in my running lights that caused noise in one ( of three ) VHF's on board.
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If your LEDs caused interference with electronics it is because they have internal driver circuits. LEDs with series resistors will not cause interference.
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Old 03-18-2013, 06:34 AM   #43
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I don't think that would make any difference. As long as the total amperage of the fixtures did not exceed the rating of the controller, you would be fine. The only caution I could find is the the output v. must remain above the input v. by some specified amount. The controllers I found were cheap enough to put one in each fixture (see post above) if you wanted to.
If you are regulating the current, you would have to have a fixed number of LEDs (a fixed load). You could not turn individual LEDs on and off.

If you are regulating the voltage, you could turn LEDs on and off within the capacity of the regulator. However, you would be back to the series resistor method with its disadvantages.

If any of you guys seriously want to learn about this stuff or actually attempt it, you need to get on an electronics forum, not a boating forum.
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Old 03-18-2013, 07:53 AM   #44
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Originally Posted by skidgear View Post
In an earlier post, rwidman commented that a controller for the whole boat would not be practical because as you turned lights on and off, the current requirements would change. I was trying to understand why that would be the case if the dc-dc power converter was sized big enough to handle all the lights in the circuit, and all the bulbs in the circuit were matched to the characteristics of the converter.
I understand the concepts between the two ways of getting the most out of LEDs without the issues....

A rated high enough DC-DC converter would be fine...as long as it provided the voltage that ALL the seperate LED bulbs/fixtures liked. I would run it to a fuse block with each lighting circuit fed by an appropriate fuse. Each lighting circuit would have a circuit on/off switch just in case not all the fixtures did.

I can honestly say withut crunching all the numbers for a specific boat...it's hard to say which would be more efficient and cost effective.

But my gut is telling me that if I have say 30-40 LED light fixtures on a boat...the efficiency and cost effectiveness of installing a whole boat regulated voltage supply and cheapo lights will be more cost effective and efficient than using fixtures and lights that cost 5 times more.

But one more thing...the more I think about it....I think I would only crunch the numbers if I was starting from scratch, rewiring my boat (which I am) or I had a large boat with hundreds of light fixtures. The probability that 30-50 light fixtures requiring changeout or modification to handle the better bulbs and the cost of the better bulbs isn't going to be that much different than trying all this wth cheaper bulbs and modifying your electrical system.

One advantage of going LED is that if done correctly and the better bub lives up to it's rep...once you switch...only my heirs will have to worry about whether I made the right or wrong decision...
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Old 03-18-2013, 09:07 AM   #45
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Originally Posted by rwidman View Post
If you are regulating the current, you would have to have a fixed number of LEDs (a fixed load). You could not turn individual LEDs on and off.

If you are regulating the voltage, you could turn LEDs on and off within the capacity of the regulator. However, you would be back to the series resistor method with its disadvantages.

If any of you guys seriously want to learn about this stuff or actually attempt it, you need to get on an electronics forum, not a boating forum.
You just clarified what I was trying to understand. Might have stated it earlier, but I didn't get it. Thanks for sharing the info. No need to go to an electronics forum...yet. Next question is just how much efficiency is lost with a resistor versus regulated bulb. If it's milliamps, it might get lost in the weeds.
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Old 03-21-2013, 11:47 AM   #46
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Watching a home improvement show on TV a few minutes ago, I saw that a system of LED fixtures with a common single driver is available (for 120 volts AC). A trip to the home center might be in order for anyone with a serious interest in doing it this way.
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Old 03-21-2013, 12:11 PM   #47
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Ron,
What you said about the driver being the source of interference not the LED's or LED's w/ resistors, is a good reason to accept the losses from the resistor type system. What are we actually talking about? A few miliiamps and a few lumens?
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Old 03-21-2013, 12:13 PM   #48
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Pay a little more for the LED bulbs with buck driver circuits integrated, and there should be no problems with lights dimming on voltage drops. We have used them for about 3 years with no problems. No tricky wiring or fixture changes. Just replaced about 50 bulbs. Very happy so far. It is nice not to have to worry about someone leaving a light on. They also work on regular 12 V dimmers. Many different types and colors available.
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Old 03-21-2013, 12:36 PM   #49
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Ron,
What you said about the driver being the source of interference not the LED's or LED's w/ resistors, is a good reason to accept the losses from the resistor type system. What are we actually talking about? A few miliiamps and a few lumens?
It's not just the inefficiency, the brightness will vary with the voltage on the boat. Shorepower charger on or engine running, they will be brighter. Heavy electrical load at anchor, they will dim. For example, with the engine not running, cook something in the microwave using the inverter and the lights will dim.

For the folks saying the drivers will not cause interference with electronics, the interference will be at specific frequencies so if these frequencies do not coincide with your electronics, you will not notice a problem. Example:

I bought two LED replacement lamps with built in drivers for the lights in my V berth fixtures. They worked fine. One evening I was watching TV and I turned on one of the lights. The TV signal froze. Turned off the light and it came back. This only happened on channel seven, not on any of the other channels. If channel seven was not in use in my area, I would have never known about the interference problem.

I installed a simple capacitor filter inside the base of each lamp and that eliminated the problem.
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Old 03-26-2013, 08:10 PM   #50
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Interesting thread. My boat was originally lamped with 12" fluorescent fixtures that had pretty much all failed. We literally had no effective 12-volt lighting. I replace all of the 12" tubes with these. They connect into the original sockets but power is supplied through the pigtail coming out of the back of the tube. I am very happy with the results and I now have 12-volt lighting that is really usable.

Marty......................
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