PARTS LIST
The original LED chosen for this flashlight was a Osram Synios P2720 KW DMLQ31.SG, hence the name of the flashlight. Unfortunately a flaw in the testing method made this LED appear very high eprforcming, despite it not actually being that great. For this reason, the Osram Oslon Black Flat is still the highest intensity LED available currently at ~260cd/mm^2. Tests of this LED can be found here: LED Test The price of one LED is $4 CAD.
The driver that will be used to power the LED is a 27.5mm MTN-MAX 1A-6A Buck Driver from Mountain Electronics. This driver can take 5V-18V making it perfect for the use of 3S lithium batteries. It will also be configured to output 6A just like the OptoFire which is about the maximum that the Black Flat LED can take. The driver costs $26 CAD.
The reflector is the most expensive part of this flashlight. It is made out of electroformed nickel plated in aluminum, a very large and high precision optic. There were several options for this reflector, such as 1 or 2 inch bottom hole and 11 or 13” diameter. In order to maximize the available area, the option with a 1” hole was chosen. Even though the 13” option would also increase the area, the LED only emits light in a 180 degree hemisphere so anything over the 12” mark would be unused area. A $100 USD fee could be paid to have the 13” reflector cut down to 12”, or an almost identical reflector could be purchased from Optiforms, the P76. The P76 is 12” diameter, and has an even smaller center hole at only .75”, however this reflector costs almost double what the Phoenix reflector costs, so for price/performance purposes it will not be purchased. The $100 option to cut down the Phoenix reflector will also not be taken in order to fit the reflector more easily inside the aluminum tube.
Overall, the 11” reflector will still perform extremely well and collect almost all of the light (96.5%) and the price is very reasonable compared to the competition. One reflector costs $402 CAD.
No radiators or fans will be used in the cooling of this flashlight, thanks to the aluminum body design. In order to transfer the heat efficiently from the LED in the middle of the reflector to the sides of the searchlight, liquid cooling will be used. Copper tubing will be used to transfer the heat from the fluid to the aluminum body. 25 feet of 3/16” copper tubing cost $42 CAD.
To move the fluid through the loop, a compact self-priming pump will be used. The pump has a flow rate of 1.3L/min and a pressure of 0.3MPa which should be enough for this small loop. The pump costs $16 CAD.
Flexible FKM tubing will be used to connect all the cooling components such as the LED block, pump, and copper coil. This tubing has a 1/4” outer diameter which will fit perfectly below the aluminum arms holding the LED block. A 3m length will be more than enough for this project as well as future projects. The tubing costs $31 CAD.
Small tubing barbs will be used to connect the tubing to the LED cooling block. The barbs have an outer diameter of 5mm which will fit tightly inside the tubing. The set of 10 barbs will cost $6 CAD.
The thermal compound used between the LED MCPCB and cooling block will be liquid metal. The three best options are Coolaboratory Liquid Pro, Coolaboratory Liquid Ultra, and Thermal Grizzly Conductonaut. Liquid Pro has better thermal conductivity than Liquid Ultra, however Liquid Ultra was made specifically because the Pro was very difficult to apply. Conductonaut on the other hand, has almost identical thermal conductivity as Liquid Pro, but is as easy to apply as Liquid Ultra. For this reason, Thermal Grizzly Conductonaut is the best of the three options. This liquid metal paste also has a higher thermal conductivity than most solders, and makes it much easier to assemble and replace the LED in the future. One gram of liquid metal costs $22 CAD.
To protect the reflector, a custom diameter acrylic lens will be used. The lens is 3mm thick and will be slightly below 12” in diameter. This ultra-clear AR coated acrylic has a light transmission above 97%. The custom size lens will cost $54 CAD.
The large LiPO batteries used in some of my other projects will unfortunately not fit inside this compact searchlight. In order to keep this a portable “flashlight” it will still require an internal battery. The Shockly 5500mAh 26650 cells are extremely popular for their very high capacity, more than the rated 5.5Ah, and discharge rate. Six of these batteries will be used in a 3S2P configuration for a total of $60 CAD.
To make the batteries easy to remove for replacement, shipping, or using external power, six 26650 battery holders will be used. The battery holders are sold individually, so six will cost $9 CAD.
A custom cooling block for the LED will need to be machined by CNC. The piece will be made outof solid copper for the best heat transmission. The CNC job costs $133 CAD.
The body of the searchlight will be made out of a 6061 aluminum extruded tube. A 12” outer diameter witha .25” wall will be very rigid to protect the reflector, and will allow 1/4” of space around the reflector for protection. This space will also be used for tubing and wires to pass from behind to the front of the reflector where the LED is. The tube will be custom cut to 4” long and will cost $192 CAD.
1/4” thick 6061 aluminum sheets will be used for both the bottom of the searchlight as well as the ‘arms’ that will hold the LED and cooling block. The 1ft x 2ft aluminum plate will cost $72 CAD.
A blue LED voltage display will be used to monitor the battery’s voltage, even though the LED driver also has low-voltage protection. It is always useful to know how much battery there is left, and if it is getting close to finished. The voltmeter costs $10 CAD.
A blue LED temperature display will match the voltage display and also give information about the LED’s temperature. The temperature meter costs $17 CAD.
A compact black handle will be attached to the outside of the searchlight for easy portability. This rubber handle folds flat to take up less space when being transported, such as in a backpack. The handle costs $4 CAD.
The sheets of metal will be cut using a waterjet due to the complex 2d shapes and accuracy needed. The waterjet time costs $18 CAD.
For the highest durability, Type 3 hard anodizing will be used on the flashlight body. This is the most durable and scratch resistant coating, and will give the flashlight a nice dark grey appearance. The anodizing costs $150 CAD.
