The wire is split to allow room for screw. These only have 16 LEDs but are about  as bright as a 12 volt fluorescent trouble light, with half the wattage draw. Great for under the deck to illuminate counters, desks etc!

From what I have seen so far, these buggers are bright when full on! Luckily these cases have a second switch that can be used for a dimmer by turning some off. The center LEDs on both boards are reserved for a few Red LEDs. This is for conditions at night that won't ruin the night vision.

While that method seems to work well, the resistors must get larger as the amount of LEDs goes up. The resistors create heat, which means the circuit is loosing efficiency to the air, power that should be going to the LEDs. High watt ( >1 watt) resistors start to get bulky and expensive. Also, the LED brightness can vary greatly from charging to low voltages on the batteries. Not at all like a bulb.

My solution is to plan out the mA draws in advance and use a regulator. I have measured these hi-flux LEDs and noticed they are fairly happy at 3.1 volts. No heat, and fairly bright, about 70% max. At 3.5 volts they are really drawing current, and at 4 volts they are getting hot! Using a 7809 regulator with a diode on the "ground" side going to ground gives 9.6 volts. 3.2 each. The diode located under one of the LEDs will pick up any heat as the LED warms. The warming diode will conduct better thus lowering the voltage. A balance can be obtained that emits minimum heat for max  brightness. I will be experimenting with 2 diodes in series to start. That will make 10.2 volts, 3.4 volts for each LED cold.

The boards are done, the LEDs are going on this week!

Yesterday, we tested the first light in the boat. It provided a nice amount of light that is plenty easy to get around under at night.  Unless one sits right under it, reading is more difficult, though not impossible, hence the reading light are strategically mounted.  The regulator idea works, but it seems the diode needs more to be near the regulator than on the LEDS. Without heat sinking, they get quite hot.

Feeding a better suited transistor to power The flux LEDs. ( Caps have been omitted )	Unfortunately there is no room for any heatsink so either I will return to resistors, or use a heavier regulator that will need to be mounted away from the board. (left) I like the amount of light they put out , any less wouldn't be acceptable ( now that I have seen how much light they put out ha ha! ) so there will be a solution. An informative fellow has posted to the forum on the subject of luxeon LEDS. These are extremely bright and relatively inexpensive now. The problem with those is a bezel needs to be integrated into the light fixture to spread the light out. With the type of fixtures we are using, this isn't an option as the whole thing would need to be built. We tested out the reading lights ( which are luxeon style ) and they are indeed a very good replacement for the halogen, and definitely bright enough. If I had more time ( and money ) I would be looking into these further. For now we'll stick with the flux style LEDS. They are still brighter and more efficient than conventional halogens in the same case. After having mounted the LED strips, we tested those as well. They do the job extremely well for under counter lighting.
Update: In the end I have ended up using 2w 12 ohm resistors to light each bank of 30. They are nice and bright and don't seem to heat up much. I may try a current regulator with a LM317 I was advised on, but really, these seem to be working great from -20ºC thru +30ºC and 12 v to 14 v without any problems. When charging above 14 v the brightness is a little alarming, but the heat is still manageable and none have burned out yet. We won't be doing much marina charging anyway.

ng wAbove the photo illustrates the low profile lights over the galley and dining areas. The both of the on at night provides ample light to work/cook/read under. What more could on ask for! The center switch position makes the light go red. Amazingly easy to see under as well.

While messing with the dash dimmer board I thought about an automatic LED controller based on PWM (pulse width modulation)  that would either (a) sense the current draw and lower or raise voltage to compensate (b) sense the temperature via a thermister and compensate, or (c) use thermal and a CDS cell to balance the max brightness without overheating the LEDs. Using a PIC chip to control a light seems silly and wasteful, but these days PICs are so cheap it's not a problem.
The only thing would be necessary perhaps would be to use a crystal instead of unpredictable RC oscillator because that may cause radio interference. Maybe one day I'll experiment with it.

Nov30 2007