I have a small shed that has no lights. I usually keep an LED flashlight by the door. In fact, a local store gives LED flashlights away free with a purchase so often I have simply replaced the flashlight instead of replacing the batteries. I decided this method was not a viable going forward and the MacGyver challenge was a little added incentive to get started. To remain true the challenge I decided try to complete the project without purchasing anything, just using what I have on hand. luckily, I have saved a lot of stuff over the years.
Step 1: First the Basic Parts
As I stated, I have several LED flashlights with dead batteries. I also have a 12 volt battery that came from a booster pack that was no longer able to jump start a car but stil held a reasonable charge (I had been using the booster pack as a 12 v power supply at times).
By my, admittedly, limited understanding of LEDs I believed I could wire the flashlights in series and by adding the operating voltages together calculate the needed supply voltage. Each light had three 1.5 volt batteries, for a total of 4.5 volts. Given the operating voltage of my power supply (12 v) I choose to wire three flashlights together, leaving the lights slightly under driven (three should have a 13.5 v power source and I had a roughly 12 v source). Being slightly under driven sould make the lights marginally dimmer but they would last longer.
Step 2: The Lights
I took the lights apart, removed the battery tray, I soldered lengths of wire to where the battery tray had been connected. I drilled a hole through the back to the flashlight and routed the wires out through the hole. I tied knots in the wire before routing the wires the holes to avoid any stress on the wires pulling directly on the connections. I also tied knot in the positive lead for each of the flashlights to identify polarity once the flashlight was reassembled.
Step 3: Testing the First Step
I wired the three flashlights in series and, to test their operation or non-operation, I connected the assembly to the battery. The lights lit, were more than bright enough and nothing smoked, overheated or popped like a fuse.
Step 4: Keeping the Battery Charged
While I could just install the lights as they are, that would require either bringing the battery to the garage or stretching extension cords to the shed to charge the battery, not very efficient, green or useful.
I have an old solar panel originally designed to hang from a sun visor and plug into a vehicle 12 volt power outlet to keep the vehicle's battery charged. The charger never worked right and discharged the battery it was connected to; time to find out why.
From what little I know of solar panels the most likely problem would be a blocking diode. The panel had an LED in the vehicle connector end (a charge indicator?). I had noticed that the LED was illuminated at all times it was connected to the battery; even when the solar panel was completely covered, this seemed like the place to start.
Opening up the connector I found an LED and resistor wired across the positive and negative terminals. I tested the panel with the LED and resister out of the circuit, with a diode checker, an ohmmeter and by wiring a 12 volt load (a license plate light bulb) into the positive side of the circuit I did not find any evidence of a blocking diode.
It appears this was built without a blocking diode (or the diode failed?) and the LED and resistor were designed to put a small load across the battery terminals to prevent the battery from discharging through the panel possibly damaging the panel (I would be interested in hearing from anyone who can confirm or refute this assumption). Time to try install a blocking diode, this presents a challenge as I do not routinely work with electronics and don't have much in the way of components readily available.
After a number of false starts I removed a diode from the printed circuit board that had been part of the booster pack the battery came out of (I have to admit I have no idea of what makes a diode a blocking diode; the ratings, load etc. Selecting the diode from the board was based primarily on easy access to the soldered connections).
I checked the polarity of the diode and installed it on the positive side if the solar panel, then checked the diode to make sure I had not damaged it; it was fine.
Step 5: Automatic Switch
I prefer not to fumble for a switch in the dark so I looked for a switch that could be triggered by the door opening. The switch I found was an interlock switch for a long defunct self-cleaning cat litter box (still have the cats, apparently too many for a self-cleaning litter box). The switch was mounted in a bracket, I thought I could use the assembly. The switch was a momentary switch so I only needed to figure out how to activate the switch to turn the lights on then spring pressure, built into the switch, would turn the lights off when whatever pressure activated the switch was removed.
Step 6: Mounting the Battery
I wanted to secure the battery out of the way and off the floor. I found the answer in an empty shelf at the top of the door to the basement.
Step 7: More Light Is Needed
The solar panel does not appear to be weather proof so I wanted to mount the panel inside the shed. The shed has windows but they are clouded restricting the amount of light entering. I had a piece of clear plastic left over from another project that seemed to be the fix for the clouded windows.
Cutting the clouded plastic did not go well, instead of a nice clean cut the existing plastic fractured repeatedly leaving a ragged edge. I cleaned the edge as best as I could and applied the new covering with an bead of clear RTV (Room Temperature Vulcanizing) sealer and the original screws.
Step 8: Puting It All Together
I screwed small hooks into the ceiling and hung the lights from the hooks.
Next I mounted the switch to the wall just inside the door, attached another hook to the door and ran two connected rubber bands from the switch to the hook. When the door is opened the rubber band pulls the switch closed and turns on the lights.
I mounted the solar panel in the new window by running the screws for the window through the straps originally intended to loop around a sun visor.
I mounted the shelf for the battery and ran the positive side of the lights to the battery, the negative I ran through the door switch to the battery.
Just before I wired the solar panel to the battery, I checked the voltage from the solar panal.
The wires that were hanging I secured with duct tape to keep them out of the way.
Step 9: Ready to Put It to the Test
Everything was in place and it worked! The lights came on when the door was opened about one third of the way and the lights went out just before the door closed.
I waited until after dark and the lights lit the interior well enough to find what ever I needed.
Step 10: Adjustments and the Parts
The switch I used had a small channel the rubber band went through, the channel did not always keep the rubber band in place. I glued a small piece of plastic over top of the channel and the rubber band now stayed in place.
I squeezed the hooks holding the lights closed as the lights tended to come out of the hooks as I "aimed" the lights. I also used the duct tape holding the wires in place to help "aim" the lights. One light pointed to each side and the third pointed to the back wall.
if the shed is in use during the day, and the lights aren't needed, to save the battery the lights can be shut off by switching any of the three flashlights off.
I did not have to purchase any parts for this. The lighting "system" was made from; flashlights I had originally gotten for free, a 12 volt battery that could no longer jump start a car, a switch from an self-cleaning litter box, a shelf that was unused where it was, a solar panel that hadn't work right, a diode from a circuit board and from the junk drawer - hooks, wire, duct tape & rubber bands.