Archive for March, 2011

March 20th, 2011

LED Shed Lights

I put in a plastic storage shed last summer and have been trying to customize it to my tastes. One thing that I thought would be cool was to add some lighting. I eventually came up with the idea of using LEDs and a SLA battery to power them. But how to make them look nice? That would soon come to me…

In early January, the orange depot was clearing out all of their Christmas stocking stuffer gift crap. I ran across their LED flashlights that were marked down to $1 each and I knew I had found my light source. I bought 8 Aluminum LED flashlights [6 LEDs in each flashlight – batteries included!]. I also got a 12v 2.3AH SLA battery and a 12v solar car battery maintainer (meant to sit on the dash and plug into the cig lighter to keep a car battery charged when it sits for long periods).

I started by cutting 2 strips of 5/8″ MDF and then drilling 4x 1″ holes equally spaced into each of them. I also made a shallow 1/4″ dado cut centered along the length of the back of the strip.

I then cut all the flashlights right behind the LED assembly and began wiring them to the board. I experimented with 7805 5v regulators to lower the 12v battery down to 4.5v for the flashlight head. I used 2 regulators (4 lights per regulator). They got really hot even with a heat-sink, so I figured that this heat was wasting lots of battery power.

In the end, I settled on using 2x16ohm (32 ohm total) 5 watt resistors running two light heads in series. So each of the 4 pairs of light heads has its own resistors lowering the battery voltage down to the proper level. I used a small relay controlled by a regular house light switch to turn the lights on and off (to try and avoid some line loss of power between the switch and the battery).

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To install the light bars in the shed, I used hanger bolts (wood thread on one side, machine thread on the other) to bolt the light bars to the metal rafters in the shed. The rafters are ‘U’ shaped, so they made a nice place to tuck the battery away in. The solar panel is held up to the shed sky-light with some safety wire. A length of phone wire connects the relay module to the light switch that is installed in a shallow plastic work box screwed to the shed wall. As you can see, the lights provide more than adequate illumination for finding things in the shed at night.

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Thanks to the folks at the orange depot for ordering too many flashlights at Christmas. Without their $1 flashlights, this project may have never materialized!