I'm looking for 12 volt LED lamps for our boat and I can find
*nowhere* that gives any sort of indication of how bright they are. How can I decide what to buy if I haven't a clue whether the lamp is the equivalent of a 6 watt incandescent or a 60 watt incadescent?I mean it's a rather fundamental thing about a light - how bright it is!
Even CFLs quote a (very optimistic!) equivalent which does at least give you a sort of ball-park figure for their brightness.
I have a few about the house. They are very peculiar things, you need to see/buy one before you buy a lot to see if you like them. Some have a very nasty blue colour as well. Even a 2 or 3 watt one gives out a lot of light. But peculiar.
Very directional and small source. Bright if you look at it - but doesn't illuminate very well.
Don't they have the light output in lumens on them?
If they do, then that's a better way to compare light output than "wattage equivalant" figures, which tend to be a bit optimistic.
Some approximate figures for 240V incandescent bulbs are:
100W 1300 lumens 60W 700 lumens
I think some of them do, I'll take another look.
Useful, thank you, I'm sure I could find that out myself but now I needn't! :-)
The LEDs which don't say are usually the lowest efficiency ones, which are 1:1 equivalent with filament lamps, and limited to 3W max because of LED heat handling problems.
LED lamp manufacturers are usually cagey about light output because most people think they are significantly more efficient than they really are, and that's not a misconception the manufacturers want to break. There are some real high efficiency LED lamps available, but expect to pay well over £50 for them.
If you are able to manfacture your own, the component LED parts are not expensive (at least, nowhere near as expensive as commercial efficient LED lighting).
That's a thought, I'm quite able to put electronics together, once upon a time (a *very* long time ago) it was my job. I still dabble and have a decent soldering iron etc.
Where can one buy efficient LEDs?
Where you you buy INefficient ones?
Cree, Luxeon, Lumileds are the names for high power LEDs
Nichia?
Yeah, and them.
And never underestimate how bad LEDs are in cheap lighting products. Had a couple of 12V shelf lamps from B&Q that I clipped to the daughter's bed (safe and not hot). They were a cluster of about a dozen 0.2" bright white LEDS - not very high powered. After about a month, the LEDs started keeling, one by one.
Got them replaced and the next set did exactly the same.
I won't buy any LED fitting now unless I know what LEDs are in it.
Luxeon is a line of LEDs from Phillips Lumileds, Lumileds originally HP / Phillips joint venture.
Cree are huge US LED miyaker direct competitor and lot of time brightness winner to Lumileds, X-Lamp is a popular line for them though they supply raw dice to people like
Seoul Semi Conductor, SSC another respected maker.
Osram have their Dragon line of big LEDs.
Shuji Nakamura invented the blue and white LED whikst working for Nichia who still make some of the nicest small whites , Nichia don`t make very high power LEDs.
Toyoda Gosei are another big Japanese name and have just signed a deal with Epistar of Taiwan for lower cost manufacturing.
Its an ever changing game with LED makers....
Cheers Adam
Also if you live on a boat (I used to) a comparison with candles is always useful. 1 lumen =3D 1 candle IIRC.
Robert
Same with the one I bought from Lidl. RO 40? replacement. Cost about 8 times the price of a tungsten one. Went bang - and I do mean bang - sooner than a tungsten would have failed.
I've found candles vary in output too. ;-)
You don't want to buy the most efficient ones because they are stupid prices and you'll never come close to recovering the price premium in energy savings. The standard 1W and 3W emitters that lots of people make now are generally fine, and are subject to price competition.
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