Fluorescent Tubes v. LED's

[nigelmercier]

... a warm white one loses some light due to the colour conversion process.

Indeed, so why would anyone want one?

 

[Roberto]

I can see what type of colour is "warm white", but what is the difference -if any- between "cool white" and "daylight white" ? Which is the one hospital-like, like old fluos ?

 

[MichaelHomsany]

Yes!

My electronics is pretty much out of date these days.
Do LED's tend to go open circuit or short out?
I was under the impression that diodes tend to go open cct.
Please note that I said tend and don't infer that I mean always

As an OEM, I've looked at almost 1/2 million high output LEDs (we do a 100% test and narrow bin of incoming LEDs), and it is almost evenly divided (at least with the Nichia that we use) between the devices failing short and failing open.

The chemistry of the PN junction of the high output (actually, they start off as being blue) LEDs is much different than the old red/green/amber indicator LEDs, which I think is what may account for the different failure modes.

One of the more interesting failure modes that we've observed is that when LEDs have been overdriven (like using an LED assembly made for a regulated source, rather than 12/24v nominal on boats), they will not always fail binary, but can begin to fail in a 'flicker' mode, at about a 10 Hz rate!

I did have one report where an LED failed in a manner which caused it to act not as an LED, but as a photodiode, but, again, please remember how many we've looked at.

Although not a true failure mode, the real key of high output LED life is the life of the reflective phosphor. Even though the PN junction might be intact after 20 years, if the phosphor has degraded, you might be able to tell that the LED is functional, but not much more than that.

Degeneration of the phosphor is controlled by basically two elements, the original quality of the phosphor, and the heat seen at the LED 'die' itself. The quality of the phosphor is the difference between the 'good' quality devices (Nichia, SSC, Phillips, Cree), and the cheap Chinese junque. As for heat, the manufacturer's literature that I've seen (but cannot share with you due to contract issues), indicate that if the junction is kept at -50*C, the life of the phosphor is basically infinite.

Hope this answers your question and best

 

[Chi34]

More stuff to read here.
http://www.marineled.fr/technique.php

 

[Adrian Jones]

I can see what type of colour is "warm white", but what is the difference -if any- between "cool white" and "daylight white" ? Which is the one hospital-like, like old fluos ?

Daylight is often the description given to a white light with a colour temperature of around 5000K. This is pretty much midway between Warm White and Cool White. There is often all sorts of vague descriptions used to describe the various white light tones, particularly by non technical suppliers. Suppliers of vehicle lamps for instance use xenon white to describe the output of their products. Presumably this is to show them as being similar in colour to modern HID lamps used in headlights

Most competent suppliers will refer to the colour temperature when describing lamp products, for instance Cool White, 6000-7000K and Warm White 2900-3500K.

The attached illustration may be helpful.

 

[sutton sailor]

LED's from RS

I replaced all of my festoon bulb internal lamps with led from RS. They were the same format and only cost £2-3 each there is a choise of warm white and cool white. I can now have all the lamps on for less amps than one old filament bulb:

 

[Roberto]

Daylight is often the description given to a white light with a colour temperature of around 5000K. This is pretty much midway between Warm White and Cool White. There is often all sorts of vague descriptions used to describe the various white light tones, particularly by non technical suppliers. Suppliers of vehicle lamps for instance use xenon white to describe the output of their products. Presumably this is to show them as being similar in colour to modern HID lamps used in headlights

Most competent suppliers will refer to the colour temperature when describing lamp products, for instance Cool White, 6000-7000K and Warm White 2900-3500K.

The attached illustration may be helpful.

thanks Adrian!

 

[Scotty_Tradewind]

I took advice from Robih and others of this parish and went to Ultraleds and fitted some of theses in various places in the boat.... http://www.ultraleds.co.uk/5050-light-strips-warm-white-lumen-p-2304.html

see the main boat/marine section here... http://www.ultraleds.co.uk/marine-boats-lights-c-99.html

One of those 39 LED fittings rated 10-30V gives off a light equivalent to a 60W domestic bulb, almost entirely eliminates shadow and uses little current.

I've stuck a couple in the galley area, one in the back of the engine bay, another in the large closet/wardrobe. I intend to put two each side in the bottom of the deep grab 'rails' in saloon as uplighters.

 

[MichaelHomsany]

...Most competent suppliers will refer to the colour temperature when describing lamp products, for instance Cool White, 6000-7000K and Warm White 2900-3500K. ...

Well, actually most use the same as COLREG does, co-ordinates on the 1931 CIE chart (re, amoungst other locations, http://www.bebi-electronics.com/specpics/colreg_color.jpg) for the same reasons why COLREG uses the CIE chart.

Dr. Curie (Madam Curie's husband, a renowed in his own right as well) developed the chart as human's perceptions of colours change not just with wavelength, but in addition with the relative intensity of the colour.

The 1931 chart is a bit dated, as better regression analysis techniques have been develped since 1931 (and newer CIE charts as a result), but it's still the industry norm for determination of all colours, not just 'white'.

 

[WoodyP]

As the OP, it seems that this post has generated not just light but a little bit of heat as well.

I feel a bit like Michael Caine in the Italian Job, I only wanted to blow the doors off, or at least have help in making up my mind.

The downside of Fluors apparently is electronic noise. For some this is an absolute problem for others they don't seem to notice it.
The downside of LED's is that unless you pay a fortune they burn your boat to the water line, or not depending on your point of view.

As neither an electrician or an engineer its all a bit confusing really, but thank you all for your ongoing input into something that I thought would only last a couple of posts.

HMMM, I wonder about starting an anchor thread now.

 

[highsally]

This info isn’t really focused on the boating world, but I suppose many of the principles still apply:
http://www.ohmsandwattsservices.co.uk/kbase/kb_0005_energy_saving_led.php