LED 12V Camping Lights

My dad needed an efficient light source for the inside of a camping van. The lights needed to be able to run multiple nights without draining the battery while still producing decent quality light. The following is the construction of such lights.

The lights use Cree LEDs with 90 CRI and efficiency of 110lm/W (400mA). A warmer 3000K color temperature was chosen to facilitate falling asleep at night. The light output is continually adjustable from 150lm (0.8W) to 900lm (10W) using LEDdynamics' BuckPuck 1000mA drivers. The lights also have reverse battery protection from P-channel MOSFETs.

The ears on top are for hanging the lights using paracord.

Materials (pictures show material for two lights)

• 1/2" aluminum plate
• 3/4" aluminum rod
• Acrylic diffuse 0.118" ACRYLITE Satinice 0D010 DF (left over from another LED lighting project)
• LED emitter Cree Xlamp CXB1304, 9v 3000K 90CRI 110lm/w, CXB1304-0000-000C0UB230G
• LED driver LEDdynamics BuckPuck 1000mA 7-32v 3021-D-E-1000
• 220uF 25V electrolytic capacitor
• MOSFET P-channel IRF5305PBF
• Power jack 2X5.5mm PJ-065A
• Cable 2.1X5.5mm 2m 10-00110
• Power jack 2.1X5.5mm 50-00025
• Cigarette lighter plug with 2.1X5.5mm plug on other end of cable (select desired cable length for light placement)
• 2X 8-32 1" stainless button head cap screws
• 2x 6-32 1/4" stainless button head cap screws
• 6-32 1/8" set screw
• 2X #6 plastic washers
• 2X #6 stainless washers
• Thermal paste
• 4.7K ohm B4K7 linear potentiometer with ON/OFF Switch (6mm shaft with flat)
• Two part epoxy
• Glow-in-the-dark powder (from glonation.com)

Tools

• CNC mill and 11/32" end mill (min 1/2" depth of cut)
• Metal lathe with normal tooling (for turning the knob, could also purchase one)
• Drill press
• Drill bits: #29, #36,1/8", 3/16", 5/16", 7/8", 6mm
• Hex keys
• 6-32 and 8-32 taps with handle
• Hacksaw blade (for cutting the tabs after milling)
• Disk sander, file and 220 grit sandpaper (for smoothing tabs)
• Soldering iron, solder and flux
• Heat gun or lighter (for heat shrink tubing)
• Heat shrink tubing to cover wiring and MOSFET

SolidWorks (2016) and STL files are provided.

• Clamp the 1/2" aluminum plate in the mill vice
• Generate the G-code for the two halves of the housing (I used tabs to hold the parts in place)
• Let the machine do its thing (11/32, 2 flute HSS end mill was used)
• Drill the connecting holes (I only drilled 1/8" for now and finished on drill press)
• Mark the LED fastener locations or drill them to size

• Free the parts from the plate using a hacksaw blade
• Smooth the tabs flat on a sander being careful not to sand too deep
• Finish smoothing with a fine file and 220 grit sandpaper

• Attach the diffuser material to a sacrificial back plate held in the mill vise (drywall screws into plywood)
• Generate the G-code for the diffuser
• Let the machine do its thing
• Remove parts from the sheet using the hacksaw blade
• Remove tabs on sander

• Drill box back holes (#29 bit) and LED mounting holes (#36 bit)
• Tap box back holes (8-32) and LED mounting holes (6-32)
• Drill box front clearance holes (3/16")

• Mark the location of the holes for the potentiometer and power jack on the two halves
• Notch the marks using a hacksaw blade (only leave a shallow cut for a drill bit to follow)
• Assemble the two halves with 8-32 fasteners
• Drill a 1/8" pilot hole into the notches
• Follow the pilot holes with a 5/16"
• Drill the center web by going through the bottom hole

• Apply thermal past on the back side of the LED and place into the holder
• Slide stainless washer then plastic washer onto 6-32 fasteners
• Install the fasteners so the LEDs are held in place
• Slide the diffuser lens into box front

• Using soldering iron attach wires to the potentiometer and power jack (remember to cover the joints with heat-shrink tubing as you go)
• Work the potentiometer and power jack into the back half of the box
• Attach wires to LED driver and apply heat-shrink tubing
• Add the capacitor across the power terminals on the LED driver
• Wire in the P-channel MOSFET and cover with heat-shrink tubing
• Solder wires to LED
• Work all components into place

Optional drop cable for LED light

The cable on the cigarette lighter can be used directly with the light but is detached easily. The drop cable screws into the power jack on the LED light allowing for more permanent attachment while still offering a separation point at the other end if excessive force is applied to the cable.

• Cut the 2.1X5.5mm 2m cable in half and solder on the power jack (50-00025) ,
• Cover the soldered end of the power jack with heat-shrink tubing

• Mix enough two part epoxy to fill the voids on either side pf the LED
• Add glow-in-the-dark powder (about 25% powder) to the epoxy
• Fill voids with mix and let cure

• Load 3/4" aluminum round into lathe
• Face the knob and add center drill mark
• Drill 6mm hole to 0.58"
• Drill 7/8" hole to 0.18"
• Knurl outside
• Part off at 0.73"
• Face other side of knob and chamfer edge
• Drill and tap 6-32 hole about halfway up the knob

• Screw both halves together with 8-32 fasteners
• Install knob using 6-32 set screw (make sure it does not rub on the case)
• Make loops from paracord to hang the light

Enjoy!