If you're an average visitor of instructables you have probably seen a number of solar rechargeable lights, often in mason jars or something similar. I have always loved the idea of solar mason jar lights. I have made a few andwith some I was not fully pleased with the result. Just like most store bought garden lights that use a solar panel my previous solar lights failed for a few reasons. Some key factors that are vital for an efficient solar light that often cause it to fail are the battery and the solar panel ratings. With most lights the battery is typically the number one problem. The battery used in a majority of them (both diy and store) is a nickel based battery and they have a short life span and are a pain to charge in most cases. The solar panel is the next most problematic. Some have a weak current and voltage output which even on sunny day can take upwards of 8 hours to fully charge. Both current and voltage need to be at a decent output. The voltage should be a few volts higher than the battery and the current needs to meet the rating specified by the battery maker. Too much current can damage the battery and too little can take hours to charge. I took these factors into consideration when making my super solar sun jar and used the "trial and error" method to help make this sun jar better than previous ones.
What makes it "super"?
The most obvious thing that makes it 'super" would be the size of the jar. I used a big pickle jar. I guess I didn't have to use a big jar but for the amount of light I wanted to throw I thought it would be a nice touch.
While the jar is the most obvious it is not the number one reason as to why it is "super". As I said above the battery used in most lights is almost the number one reason as to why they fail. Instead of using a nickel based battery I decided to go above and beyond and use a li-po battery. These batteries have a long life span, consistent output and thanks to certain charge controllers they charge quicker and more efficiently. There are more reasons as to why these batteries are better but I won't go into the details. Since I used a li-po battery I needed a charge controller. If you use this type of battery you WILL need a charge controller designed for this application. Meaning you will need a solar charge controller. They can be found online at adafruit. If you don't use a charge controller the battery will charge and discharge improperly and can expand and combust. With that being said, do this project at your own risk. Don't go beyond your comfort level.
Another reason as to why this jar is "super" is the solar setup I used. I used two 6-volt panels at .5watts each. I wired them in parallel to increase the current output which cuts down the charge time of the battery.
Finally comes the leds. In solar lights you will typically see 1 to 4 (tops) leds used. Since the leds are being driven by a 1.2 volt battery using an induction circuit, the leds won't be as bright as they could be. Now my battery charge controller has a 3.4 volt output which is perfect for my leds (rated at 4voltsmax). The 3.4 volts will make these leds shine as bright as they can without effecting their life span. Now instead of using 1 to 4 leds, why not make it super? I used 17 leds! you can use more or less but you have to keep in mind that leds in parallel will require more current thus draining the battery faster. The 17 leds can light up a room, an outside table, a tent and even a car!
Step 1: Things Needed
For this super build you will need;
One jar, size depends on your prefrence
17 (more or less) white leds
300 ohm pot/trimmer. If you want you can use a higher rated pot. I am using the 300ohm so I can have the leds on no matter what resistance is being used.
A solar rechargeable li-po battery with charge controller. You can find these on adafruit. The portable solar USB ones should work just fine . Just be sure to use a resistor after the 5 volt output and before the leds. You must use a charge controller designed for this application. You will get better results doing so.
Solar panels. You need to get solar panels that meet the charge controller rating. For example if your controller needs a 5 volt panel you should use a 5 volt panel. Now if you want to use more than one solar panel be sure to run them in parallel so you increase the current output and not the voltage. If you run them in series you will double the voltage and it could damage the controller and the battery as well. If you have a ampmeter you should measure the solar panels current and see if it meets your controller needs.
Aside from the parts you will need tools to complete the task. You will need the basics, soldering iron, hot glue gun, electrical tape, etc.. You will also need glass bead glue so you can mount the panels to the jar without having to worry about heat effecting the strength and security of the bond.
Step 2: The Solar Panels
Since we want to cut charging time down a bit we will need to wire two or more solar panels in parallel. This step is easily done by taking the positive connection from one panel and connecting it (soldering) to the other solar panels positive connection. You do the same with the negative connections. After they are wired in parallel, assure they work and hot glue them in the jar. Be sure to leave about 5 inches of wire from the solar panels so you have enough to wor with. We will need to connect them to the solar input of the charge controller. After the hot glue sets you can secure it using the glass bead glue. Make sure to mount them in the jar facing out. If your jar has sticker residue on the outside then try to avoid that spot or clean it using goo gone. Over time the residue will clear up.
Step 3: Placing the Charge Controller
We want to keep the visible part of the jar free of any circuity. With the acception f the solar panels of course. So where do we put the charge controller and battery? For this we will use the lid. there is plenty of room and it is out of view. If your lid is conductive you will need to insulate it using electrical tape. I used a small amount of hotglue to secure the battery to the inside of the lid then placed the controller on top of the battery. I mounted the switch that came with the controller inside the jar aswell to keep it water proof.
Step 4: The Leds
You need to find a way to mount the leds at the top of the jar just below the mouth. I used a piece of perf board to hold mine. You can pick up perf board from radio shack. I soldered them with 7 on one side, 7 on the other side and 3 in the middle. Make sure the polarity of the leds are correct.
Step 5: The Trimmer/potentiometer
We will be using two legs of the three legs of the pot. There are 2 legs close together and one leg by itself. You can just snip off one of the two legs that are close together. Since I used a PCB/perf board I wanted a secure mount for the pot. Since the leds will be facing down the pot had to be mounted on the reverse side. You will need to sodler one lead of the pot to the positive leads of the leds. Since the leds are all in parallel where you solder it really doesn't matter. Just as long as its on the positive lead of the leds. The other lead of the pot will need to be soldered to the voltage output of the battery.
Simply put, you are placing the pot between the led (+) and the voltage output (+)
I have included a wiring diagram at step 7.
Step 6: Leds to the Jar and Final Connections
The build is coming to an end. Mount the leds at the mouth of the jar using hot glue. Make sure they are low enough for the lid to close. After the leds are secured you can make all the final connections. Solder the led wires to the output of the controller, solder the solar panel wires to the charge controller and insulate! Make sure the polarity of the connections are correct. Insulate any bare wires using electrical tape.
Step 7: Wiring Diagram
Step 8: Finished!
Screw on the cap and let it charge! Then at night let it light! Your super solar sun jar can now be used to light up just about anything! Thanks for reading and I hope you enjoyed :)