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post #21 of 24 Old 09-21-2013
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Re: How many lumens do I need

I was looking at lighting for a totally different application recently. One point of reference that I could relate to and found useful - a "standard" household 13W compact florescent puts out about 500 lumen.

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post #22 of 24 Old 09-21-2013
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Re: How many lumens do I need

I have experienced radio (VHF and FM) interference from an LED, and surprisingly, it was a couple of Sensibulbs, which are known for not doing this. Perhaps I got some from a bad batch. Some ferrite cores around the wires seemed to help.

We've been very happy with Marinebeam replacement bulbs. I can't agree at all with MarkSeaOfLife that LEDs are ripoffs--the meager power usage alone makes them worth it, let alone the longevity. It's wonderful to not have to worry guests (or even worse, my wife!) about their light usage. I think LEDs are one of those things where it's worth getting the good ones.

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post #23 of 24 Old 09-21-2013
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Re: How many lumens do I need

LEDs all come with lumen, candela, beam spread specifications from their manufacturers but the folks who resell them "cheap" often don't give you specs because they are buying job lots.

For instance, a prime quality white LED from Cree or Nichia may come off the assembly line and then it is sorted--actually tested and sorted--to become nine different groups of LEDs. They may besplit into 3 brightness levels, comparably 1x, 2x, 4x brightness relative to each other, and then three different "white" levels. All from the same production run. If you want the bright ones you pay more. If you don't care about a 4x difference in brightness, you can buy an unsorted batch cheaper.

So, no specs? You're buying odd lots cheap, and that can be OK if you buy a lot of them and aren't too picky about anything but price.

Lumens also may not be the best way to compare. Lumens, candela, lux, all are ways to measure brightness but they differ in how they are measuring brightness and area. See to get some idea of how those all work.

But again, LEDs are all spec'd as having a certain brightness over a certain area. Some have a ten degree beamspread, some 180 degree, etc. and they'll tell you that spread is the "cone" from brightest to half brightness, the idea being that if you set them up with overlapping cones you get even brightness from an array.

There are 50-watt and 100-watt LED "spotlights" and floodlights these days too. I've used a couple as "wall washers" indoors to light up a room. In a boat cabin it would be some job trying to conceal the light source from something that bright to let it spread around without blinding you.

Then there's the question of individual taste and eyes, what is bright enough for a kid is often too dim for older eyes to read by.

I'd suggest going to a hardware store, buying a couple of different AC bulbs (that usually have brightness ratings on them these days) and trying them out to see how much light you want. Or, looking up the numbers for AC bulbs you already have. Then look for similar ratings--for brightness and spread--on the LEDs you want.

Expect the ones that are both bright and wide beam to be expensive, compared to the cheap stuff. If you can find a vendor with a good return policy, it may pay to buy a couple of different ones, try them out, and return the ones that don't suit you, because the numbers are all well and good but there's still the question of what you LIKE.
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post #24 of 24 Old 09-21-2013
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Re: How many lumens do I need

As to inference: not all LED's have switching supplies.

Actually the cheaper and/or less bright LED's will tend to have simple resistors or possibly linear regulators which pose no threat for interference with other electronics.

Also if the module/bulb has many individual LED's on it it's less likely to have a switching supply. If it has a single LED in it, it will almost certainly have a switching supply. And high quality nav/anchor/spreader modules are likely to have switching supplies.

My alpenglow cabin lights have 3 led's in series and a linear regulator.
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