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Old 22-02-2010, 09:04   #16
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Christian,

Would the spot make a good reading bulb?

Chris
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Old 22-02-2010, 11:09   #17
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Originally Posted by teneicm View Post
I thought one of the issues with using LEDs intended for home use on a boat was the fact that LEDs are very sensitive to voltage highs/drops and that unless you have some circuitry that insures they are fed a constant voltage, the varying voltage from your battery bank can cause them to fail? Obviously this is not an issue for home use as your power source is pretty stable. Anyone have thoughts on this?
LEDs are in fact constant current devices, but like all semiconductors they are susceptible to voltage spikes and overvoltage situations. Since the DC system of a boat tends to have lots of spikes caused by inductive loads (electric motors for the most part). My boat, with electric winches, electric heads, electric pressurized water (both fresh and salt), electric windlass, not to mention engine starter motors, particularly concerns me. I'm still in the planning stages of my changeover to LEDs, but with the costs I'm looking to protect them. I'm considering putting all my LEDs on an isolated buss and protecting it with a spike arrestor. I've been considering the device at the following web page. Has anyone else used it?

STO-P Power Fault Protectors
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Old 22-02-2010, 14:09   #18
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That's correct, the 220/110V version requires an inverter (but the 220/110V version is better than twice the LED's efficiency too).

But the 12V from Steca is a 12 DC, no loss, and still way more lumen/Watt efficient (I do not mean better, because there are all other factors as mentioned by Noelex).

(Yes, yes, I know it all belongs to a separate thread and I might be distracting - apologies to all!)

b.
The 46 to 50 luments per watt figure quoted for the CFL is the total for the output of the bulb over 360 degrees. When you mount this in a light fitting some of the light will be emitted behind the globe. This is especially true of boat fittings where height restrictions prevent the filament being mounted vertically. Even assuming the best case of a vertically mounted filament in a luminare that projects well below the ceiling heights, no reflector is perfect, particularly, with a bulky CFL sitting in light path.
If you want to compare apples with apples the lumen per watt figure for the bare emitter (“Globe” only) for the more recent LED’s are

Cree Q5 85 lumens per watt
Cree XP-G 111 lumens per watt

Cree have just announced they have achieved 208 lumens per watt, so we should be seeing further improvement in the near future.

Because they emit the light over 180 degrees instead of 360 degrees the achieved light output, in a fitting, will be higher for a LED than for a CFL with the same lumen per watt figure.
The major problem of CFL on boat however is not the efficiency , but the availability of only relatively high wattages.
For the wattage of a single CFL I can, and indeed I am at this moment illuminating my boat with LED, reading light for myself and my wife, a couple of lights for food preparation a light over the nav table an anchor light and another LED’s providing general illumination.
I would need 2 or 3 CFL to duplicate this illumination, with a corresponding increase in power consumption.
CFL are ideal for producing large amounts of light over a broad area when they can be mounted high with a luminare that takes advantage of their 360 degree light production. These conditions do not exist on an energy conscience yacht with low ceilings.

I suspect these LED offerings from Phillips are using out of date LED's , but to claim they are provide less efficient illumination than a CFL by comparing the output of the bare CFL globe against the total LED fitting is flawed.
Sorry for the distraction
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Old 22-02-2010, 14:25   #19
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Originally Posted by teneicm View Post
I thought one of the issues with using LEDs intended for home use on a boat was the fact that LEDs are very sensitive to voltage highs/drops and that unless you have some circuitry that insures they are fed a constant voltage, the varying voltage from your battery bank can cause them to fail? Obviously this is not an issue for home use as your power source is pretty stable. Anyone have thoughts on this?
LED fittings often have a poor reputation because there is lots of junk available. It is very easy to overdrive poor quality emmiters with designs that have no thermal managment. The light output is ok but the lifespan can be very short.
I am still using LED globes in my Yacht the have been used every night for the last 3 years and I expect them to last much longer. In fact I was still using a home made anchor light from 15 years ago untill lightning took it out together with most of my electronics. All but 3 of the LED's survived the lightning.
Well made LED lights will have a very long life on a yacht.
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Old 22-02-2010, 17:06   #20
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noelex - informative! THX
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Old 22-02-2010, 18:08   #21
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Quote:
Originally Posted by witzgall View Post
Christian,

Would the spot make a good reading bulb?

Chris
Neg, too tight a light pattern for me. The flood makes a GREAT reading light, far as I can tell. As for driving these bulbs with DC, my guess is that they have some sort of pulse mod regulator inside...but I cant be sure. I'm going to try to contact the manufacturer...wish me luck!
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Old 22-02-2010, 18:44   #22
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If you happen to have a light meter for photography use that to measure the lumens, most manufactures over rate their outputs, some by 30%. Some measure at 1 foot and others 3 feet.
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Old 24-02-2010, 14:51   #23
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Here's the answer we've all been waiting for :

"Thank you for contacting Philips Lighting. Philips MR16 LED products operate on both 12v DC and AC.
Kim
Customer Care Associate
Philips Lighting North America"

There you have it...we are good to go!
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