hi
a workmate suggested i use LEDs instead of 12v bulbs for lighting on my
28ft yacht. i have house & engine battery and although i live aboard the
cabin lights dont get a lot of use, but nav lights are generally on all
night. has anyone had any experience with replacing conventional lighting
with LEDs? Would i need a step down transformer on the ligting circuits
because the LEDs are generally 4volt?

cheers
bruce

They do have direct replacement LEDs that run on 12V. One point to be aware
of though. I don't think any of the LED nav lights have type approval or
whatever the USCG requires. I know they don't approve specific equipment,
but there was a discussion somewhere that technically, you aren't legal if
you're using them right now. That doesn't mean they aren't available though.
That all said, see:

http://sealite.com.au/product_page.php?prod_code=SL-05
http://www.deepcreekdesign.com/
http://superbrightleds.com/


--


Keith
__
"It's easy to get good players. Gettin' 'em to play together, that's the
hard part." - Casey Stengel
"bruce" wrote in message
news
hi
a workmate suggested i use LEDs instead of 12v bulbs for lighting on my
28ft yacht. i have house & engine battery and although i live aboard the
cabin lights dont get a lot of use, but nav lights are generally on all
night. has anyone had any experience with replacing conventional lighting
with LEDs? Would i need a step down transformer on the ligting circuits
because the LEDs are generally 4volt?

cheers
bruce

hi bruce,

if you use normal LED`s to replace the lights, you will have to to use some
resistors to limit current of the LED. Flow voltage of LED`s is between 2
and about 4 volts and depends of the colour of the LED`s.
One ebtter way is to use LED`s with a constant current device built in, they
work with 12 V DC. But most of that LED`s don`t give a lot of light...
Best way will be to buy LED headlights, they fit into a normal halogen lamp
housing.
Take a look at the following (german) site to get some impressions:

http://cgi.ebay.de/ws/eBayISAPI.dll?...tegory=30 468

Juergen

"bruce" schrieb im Newsbeitrag
news
hi
a workmate suggested i use LEDs instead of 12v bulbs for lighting on my
28ft yacht. i have house & engine battery and although i live aboard the
cabin lights dont get a lot of use, but nav lights are generally on all
night. has anyone had any experience with replacing conventional lighting
with LEDs? Would i need a step down transformer on the ligting circuits
because the LEDs are generally 4volt?

cheers
bruce

LED can only absorb a certain amoung of power. Usually a resistor is
wired in series to limit the current but the resistor will eat some
power too. The formula is R = (Supply voltage - LED voltage)/LED
current (in amps) For example a 4V 25 mA LED run with 12V requires a
320 ohm resistor. ( (12-4)/.025 ) The same amount of current flows
through both the resistor and the LED but the voltage across the
resistor is twice that of the LED so the LED will use 97 mW and the
resistor will eat 194mW. YOu can put 3 or 4 LEDs is series and waste
less power but you are not going to get maximum brightness.

Also, LEDs are very directional. They may work fine for a map light but
it would take several carefully arranged LEDs per fixture to get wide
coverage.

The high power LED nav lights like Deep Creek use pulse width modulation
(a little oscillator type thingie) to blast a whole bunch of LEDs with 2
or 3 times the rated voltage but only for half to 1/3 the time so the
average power that the LED sees is within its limits. The result is
more light with less power wasted.

The main thing they have going for them is an almost infinite life
spand. From what I can gather, LEDs with high tech drivers are great
for anchor and tricolor bulbs that are on all night but with only a
small improvement in efficiency over florescents, don't seem to be cost
justified for interior lights.

bruce wrote:

hi
a workmate suggested i use LEDs instead of 12v bulbs for lighting on my
28ft yacht. i have house & engine battery and although i live aboard the
cabin lights dont get a lot of use, but nav lights are generally on all
night. has anyone had any experience with replacing conventional lighting
with LEDs? Would i need a step down transformer on the ligting circuits
because the LEDs are generally 4volt?

cheers
bruce

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com