I have started to install custom LED lighting in deLight. Light fixtures are a nuisance. The light is great around the fixture and not so much in the shadows. I had a couple of tube lights strung around the main salon on they provided a nice even light albeit not very bright and highly inefficient.
I decided to replace the tube lighting with custom LEDs. This is a sequence of 3 posts starting with a simple solution ending with a complicated but very nice and very efficient solution.
Note: You need good soldering skills and access to a milling machine. Otherwise, this custom LED lighting project is prohibitively expensive.
The objective is to replace the brown sponge trim tube in places where we want light with a white plastic tube with LEDs. I used 20mm POMC white plastic tube milled with 2 flat sides at 90 degrees to fit in the corner. A 5 mm channel was milled down the center for wiring. 5mm holes for the LEDs were drilled approximately 3.0 cm apart. See sketch.
For each piece I measured the exact length and allowed 2.0 cm at each end. then figured the number of holes needed - (Remaining length/3.0 cm). Since we are going to use groups of 3 LEDs, we need to have a multiple of 3. Round the number of holes up or down to be divisible by 3. Calculate the hole spacing by taking remaining length divided by the number of holes minus 1.
Simple calculation: 9.8cm piece (9.8cm -2.0cm - 2.0cm) = 5.8cm, (5.8cm / 3.0cm) = 1.93, Round to nearest multiple of 3 = 3, Hole spacing is 5.8/(3-1) = 29mm i.e. holes at 20mm, 49mm and 78mm.
Use the milling machine to accurately place the holes. In deLight's main salon, there were 10 pieces with hole spacing between 28mm and 34mm. As long as the holes in any individual piece are spaced identically, the eye does not notice the difference piece to piece.
Next step is to make the LED triplets. I purchased Cree 2500K color temperature LEDs for an incandescent like color. The higher the color temperature, the more white the LED. i used the individual plastic tubes as a fixture to solder 3 LEDs and a 270 Ohm resistor together. Remember each segment may have a slightly different hole spacing.
Insert the triplets into the segment and wire the negative ends together and the positive ends together using the milled channel.
This is the simplest LED setup. 3 LEDs and a resistor wired directly to your battery DC supply. This circuit powers the LEDs with 20ma at 14.4v allowing for battery charging without damage to the LEDs. The downside of this circuit is the lower the battery voltage, the dimmer the light. At my chargers 13.2v float voltage the LEDs receive 15ma. At 12.6v, battery fully charged - about 10ma. Efficiency (Power to LED / Power In) is about 60%
I use this circuit in lockers and storage places that are routinely accessed while attached to shore power. Next, I will describe using a DC-DC converter to have full brightness no matter what the battery DC voltage is.
Max