Hi, my name is Corwin and this instructable will be a guide for the process I used to build six solar powered charging stations as part of my Eagle Scout project for Boy Scouts. My main goal when I designed these stations was to make it easy to replicate and buy parts for. Please leave comments down below if you find better deals on parts or have a better way of doing something. I'll be glad to hear your input. So, let's begin with a parts list and cost estimate....
Step 1: Parts List
So, obviously I tried to make this as cheap as possible since I needed to make six of them. Again, if you find better prices or have a cheaper way to make it, please share so everyone can benefit.
6 - 10 Watt Solar Panel - $40 each from Amazon -Link -
6 - 3 Amp Charging Regulator - $10.50 each from Amazon -Link -
6 - 12 Volt 7 Amp Hour Sealed Lead Acid Battery - $17.37 each from eBay -Link -
12 - Inline Fuse Holders - $1.98 each from Amazon -Link -
3 - 5 Amp Fuses - $1.98 for 5 pack from Amazon -Link -
1 - Assorted Heat Shrink Tubing -$10 from Amazon -Link -
6 - Three Way Car Lighter Socket Splitter with USB port - $1.49 each from Amazon -Link -
12 - Mini USB Car Charger Adapter - $2.39 each from Amazon -Link -
1 - Assorted Spade / Ring Connectors - (Free) Already had
1 - Assorted Wire - (Free) Already had
Electrical Components Subtotal - $484.54
Body Components - All Purchased from Browne's Lumber
2 - 1/2 inch sheets AC Plywood 8ft*4ft - $25 each
3 - 4x4 Treated Post 12ft - $15 each
3 - 1lb Box Assorted Outdoor Screws - $12 each
12 - 1/4" x 6" Hex Bolt - $.79 each
24 - 1/4" x 1 1/2" Hex Bolt - $.22 each
36 - 1/4" Locking Nut - .14 each
2 - Metal Plumbers Strap - $3 per roll
1 - Ladybug Red Flat Outdoor House Paint - $15 per quart
1 - Box Assorted Screws - (Free) Already had
6 - Quikcrete - $3 per 60lb Bag
6 - Hinge Sets - $3.50 per set of 2
6 - Black Handles - $.75 each
Body Components Subtotal - $194.30
Grand Total - $678.84 for six or $113.14 each
Please note that I live on San Juan Island in the Pacific Northwest of USA. Items bought here tend to cost more than if they were bought on the mainland, so it is entirely possible to build this cheaper.
Step 2: Building the Box
To keep things simple I decided to go with a box to hold all of the electronics and for mounting the solar panel. To give myself a rough idea of what it would look like, I created a 3d model of it using Google Sketchup. This was not entirely accurate, but did give me a starting point for cutting wood. As well as storing the charging electronics, I added a closed off area where people could leave their devices without having to worry about them getting wet in the rain. Otherwise, the whole box could have been smaller. I changed the design as I worked on it, so I'm sure there are much better ways of building this. I also forgot that the panel would need to be angled, which could have saved me a lot of the headache involved with accurately cutting wood. However, for the sake of this instructable I will show you how to build the ones I ended up with. You can modify this design to suit your own needs. For the solar panel mounts below, you will need to do a google search to find out what the best mounting angle for you panel will be based on your location. Because I am fairly far north, mine was 45 degrees with the panel facing south. The equator would be straight up. Equivalent distance in the southern hemisphere would be 45 degrees facing north. You get the picture.... Google will answer that question for you.
You will need... (All orientations as though facing front of box)
2 for top and bottom - 10 5/8" x 10"
2 for left and right - 9 5/8" x 1'
2 for front and back - 10" x 1'
1 Shelf - 9" x 9 5/8"
2 for mounting solar panel - ?" x ?" (right angle triangle with corners cut off and modified for the angle based on global location) (Look at the pictures if you're confused)
1 six foot section of treated 4x4 (Just cut each post in half)
Building Steps (feel free to modify)
1. For the front panel, cut a 8.5" x 9" door out out of bottom right hand corner (see picture). This will leave 3" up top for electronics and plenty of space for mounting hinges.
2. Start by screwing the back panel onto the bottom panel from the bottom, making sure the edges are fairly flush.
3. Do the same with the side panels, but make sure they are inside the boundaries of the bottom panel. None of the pieces should be OUTSIDE the 10 5/8" x 10" limit of that bottom panel. Everything fits within it. (Just so you know :) )
4. Next, screw in the top panel.
5.Now, the front door should have been cut out of the front panel. Screw the shelf in from the front with the shelf directly in the middle and lined up flush against the top of the door cutout (Might need pics for this one).
6. Next, add hinges and knob to your door and attach it to the strip of wood you have left on the front panel, making sure things are lined up well.
7. Then, place your completed front panel into the box and screw in from the front. You may need to sand things down if they won't go in.
8. Lastly, from a birds eye view with your new door facing you, Screw in the triangle pieces from the narrow side 1 1/2" from the front and 1' in from the side. This should leave you with two strange looking triangles sticking up and angled towards you.
Refer to the finished pictures if you get stuck....And yes, I did leave off the post for the moment as it makes adding the electronics much easier. Also, these photos are when the boxes have electronics and no triangles since I didn't take any before they were put in...
Step 3: Adding the Electronics
Now to the fun part....
1. With the front panel / door facing you, mount the charging regulator near the top right corner on the shelf with Philips screws.
2. Turn the battery sideways as shown in the picture with the contacts closest to the door. Make sure there is extra room on all sides and mark the edges where the battery sat with a pen. Drill a hole past where the battery should sit and close to the door. Using this hole, bolt the plumbers strap in place. Put the battery back in and bend the strap as necessary to end up on the opposite side. Find and open hole that can reach the wood and drill another hole in that location. Bolt it again. Lastly, drill a hole on the other two sides of the battery and place the bolt through with threads up. This was my cheap solution to keep the battery from moving since the bolts act like bumpers if it shifts at all.
3. Next, measure the distance from the battery contacts to the charging regulator cut a piece of wire a little bit longer than that length. Crimp a spade connector to one end, strip the other, and screw it down into the charging regulator's battery negative contact.
4. Take your inline fuse, which should be long enough to bridge the previously mentioned gap, and do the same thing as the previous step for the positive terminal.
5. Then, take one of the three way car lighter socket splitters and cut the plug off. Open the plug up and figure out which lead is positive and mark it. (It will be the center pin on the plug). Strip both leads and add another inline fuse to the positive lead. Heat shrink this connection to make sure it is protected. On the charging regulator, there should be one symbol that is a lightbulb. These are your load connections. Same as before, positive to positive and negative to negative. The circuitry will shut off power from the battery to this splitter if the battery voltage is too low, so you don't ruin it.
6. Drill a hole in the top panel of the box ( not this shelf ) and feed about two or three feet of cable trough it. Again, you will need two leads. Mark one lead as positive on both ends. Strip the two that will be in the box and screw them down into the solar panel connections on the regulator.
7. Before you go any further, plug a fuse in to both holders and make sure things seem to be working.....A voltmeter is your friend at this point.
8. Drill off the edge of the rear right hand corner to feed the wire from the splitter down into the main area of the box.
9. Tighten down the wire connections one last time to make sure you don't need to open it again.
10. Feed the wires through as you place the front panel / door / shelf assembly back into the main box and screw it back together. Make sure you have the fuses in!!!!
11. Now, take out two of the screws on the side of the car splitter. Position yours somewhat like is shown in the pictures and drill one hole where you think there is one on the splitter. Measure the distance between the screw holes and drill another hole for that. Then, using longer screws, cinch it down against the inner wall from the out side.....Pictures will be very helpful for this step....
Now it's time for mounting the panel!!!
Step 4: Mounting the Panel
Okay, we're almost done..... Sorry about not having pictures of this yet. I will go out and take them today....
1. Drill a hole in the middle of the triangle along the top edge. Do this to both.
2. Cut down, strip, and crimp ring connectors to the solar panel leads coming out of the top of the case. Make sure to remember which one is positive.
3. Take off the screws from the junction box on the solar panel and screw through the spade connections while observing polarity.
4. Once finished, take one of your 6" bolts and thread it first through the outside hole on the solar panel and then through the hole you drilled in the wood. Follow suit on the other side and lightly place a nut on each. At this point I would suggest making / using spacers to give the bolts something to cinch down against so it doesn't move around. When you have that done, really cinch those bolts down.
5. Now measure the gap between the upright triangles from the back and cut a piece of wood to fit it. Screw it in from both sides to give the entire setup some extra strength.
Step 5: Final Testing / Mounting / Finshed!!!!
Plug something into one of the usb ports and make sure it's working. If so, leave something plugged in until the device shuts itself off from low voltage (make sure to cover the solar panel with something for this step). Then, place it in the sun for a while, come back, and make sure it turned back on and is working properly. If everything checks out, you are ready to put on the post.
Remove the bottom panel from the box and drill a hole in the center. Take your post and drill another hole in the center. Screw the two together, but not all the way tight. Once you have everything squared up properly, drill another hole through both the bottom panel and post. and add another screw. This should keep it from moving. You can now add a couple of extra if you want to be extra sure it doesn't fall off.
That's it, you're done!!!!! You can add paint if you want to, but otherwise, dig a hole in the ground and either cement the post in or pack dirt around it. Make sure you face the panel in the proper direction for your global location and watch your devices get charged by the sun.
Thanks for taking the time to view my project. I'm sure there are many things I could have done better, but I learned a lot while making these and hope to improve the design on my mark two model. Let me know what you think and what ideas you have for mark two!
First Prize in the
Green Living & Technology Challenge