A Simple Solar Charging Station

        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. 

Electrical Components
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.

Comments

[GeekTinker]

Are you worried about people damaging the boxes or stealing the parts?

I like your Instructable, however to avoid vandals and thieves who will take advantage of a target of opportunity, I would suggest mounting the solar panel and battery on a much higher post, far above the height of a human being. It would get more sunlight and less susceptible to being damaged or taken by the unscrupulous.

[triumphman]

Exactly, who would leave an expensive toy on a charger for hours, while hiking? When you returned to the charger, only to find your costly toys gone!! NOT ME! NO WAY!

[caperren]

Yes, this was a minor concern, but I didn't have enough time to add that into my design since the entire project had to be finished by today. To help deter people, I epoxy'd over everything that I felt would be worth getting at once I made sure the station worked.

[triumphman]

All those parts (6 of each)! Must have cost a bundle from all the different sources for the shipping! Wow!

[caperren]

To be fair, it did cost more than it could have were there appropriate stores to purchase parts for this project at in my hometown. However, since I live on an island with very few stores on it, most parts were only available to me through online sources.

[triumphman]

This whole thing is sold at Tractor (China) Supply store! It has been around for a long time! It charges electric fences! We have them on horse, cow, pig and chicken farms. So why did it win? Oh, right, the headquarters for this site is in San Fran.! They don't have farms there. Oh well, sorry! FYI

[caperren]

Yes, I am aware that there are similar items for sale that may be cheaper, but this was a project that interested me, and since I like building things myself the extra cost to make it diy was worth it. Also, considering it was an eagle scout project, it would have been dishonest for me to simply buy pre-made stations. That's wouldn't really leave me with much of a project.

[triumphman]

If you leave your stuff charging and go hiking you can kiss your expensive toys goodbye! Too many dishonest people out there! It takes hours to charge stuff. You can bet my stuff won't be there! FYI

[caperren]

There aren't hiking trails at the park where these were placed, so that wasn't much of a worry. I figured most people would keep an eye on the box from their campsites since they're visible from almost every one. Before I put the charging boxes there, people would leave their phones and devices in the public bathroom and leave wires trailing in the sinks. I figure this was a better alternative and a fun project to put together. And if you're worried about theft, then there's no one telling you you have to use the station. It just there for convenience.

[triumphman]

Tractor(china) Supply store sells these for a lot less! They have been around for a long time! They charge electric fences with solar low voltage setups for horses, cows, pigs and chickens too! You can adapt them to charge USB devices (phones, ipods & ipads, and more!) FYI

[caperren]

This is essentially a repost and I already covered my views on this topic above....

[kill-a-watt]

What are you charging? Cellphones? Battery powered scooters?

It looks like you are using the solar cells to charge a gel cell and providing cigarette lighter sockets or something.

A circuit diagram would sure be helpful.

[caperren]

These went up at some local county parks for people to charge cellphones, ipods, global positioning devices, etc....The solar panel is charging a sealed lead acid battery, which is then providing 12 volts to the lighter socket splitter. Two of the three slots have car lighter to usb adapters epoxy'd into them. I was planning on making a circuit diagram, but I made this later last night, and decided I would add it later once I redownload TinyCad.

[triumphman]

Who would leave their expensive toys on a charger, out in the park? Then go hiking! Then only to find the expensive toys were stolen! NOT ME! NO WAY!

[jsilvers1]

to me the only thing that would make it better is if u added the means to put a small wind generator attachment so when the sun is not out u could still get some power but other then this is the greatest one i have seen

[caperren]

Yes, that would be a rather nice addition. If I ever have some extra money, I'm going to build one for myself and include some features that this one doesn't have, and maybe I'll have to look into that when I do. I'm also glad that you like it otherwise.

[Tampaguy]

Noticed that your parts list showed:
"2 - 1/2 inch sheets AC Plywood 8ft*12ft - $25 each"

The only ply I've ever seen is 4' x 8' - I think either you have a very special supplier, or perhaps you just mis-stated the item.

Just curious

[sguzzi]

He put up " Body Components - All Purchased from Browne's Lumber
2 - 1/2 inch sheets AC Plywood 8ft*4ft - $25 each " Not 8ft*12ft. just saying

[caperren]

No, he was right. I changed it to 8x4 when I he mentioned it, so that's why it says it now.

[caperren]

Nope, you were right....I have changed it to be 4' x 8'. I just happened to skip over that error when I was writing this late at night.

[skylane]

Sheet goods can be acquired in 4'x 12'.
4'x 8' is more common because it's easier to handle and more convenient for
"home use"

[sushixxxx]

Is it water proof?

[caperren]

It should be. All of the joins in the wood were done so that water would fall off and not pool and seep inside. the only place that might let a little bit of water in would be the hole where the wire for the solar panel is, though because the solar panel is directly above it, water should be directed away from it. Otherwise, a little hot glue to fill in the hole would fix that potential problem.

[gkern]

Thanks nice simple design used it with a larger 12v battery, and a 15 watt solar cell. Thanks for the overall design made nice and simple which I put in a plastic tool box for portability.

[gbearpdm]

Could you run an inverter on this to run C-Paps all night? Would be nice to make a portable version for my scout camp for the adults who need electricity to run these machines at night. I love the idea and will be doing some for our camp either way.

[Ernest12]

You would need to charge deep cycle or dry cell 12 volt 100 amp or better batteries to power your C-PAP machines. That is my experience with mine.

[caperren]

It depends....I don't know how much power those machines have. Though I would guess that in order to run one for an entire night, you would need a larger battery pack and a larger solar panel. But it really does depend on how much power it pulls. Good luck with your design!

[ferjanyen]

Hi, it will be cheaper to buy just one solar panel of 60 or 80 watts,
only one regulator and only one box to house the lot and then charge 6 batteries
if that is what you aim to do or make the whole thing transportable by making it with 3 folding frames and one regulator etc.etc.
Look at the Radio ham books in your country for ideas.
Good luck, [e-mail]

[caperren]

That's a good idea. But in this case, they needed to be in many locations and immovable, otherwise I would have done something like that.

[ferjanyen]

Okay, I understand now your project. Look in Radio Amateur Leage books for voltage regulartors for solar panels and you will see that they are quite easy to make your self, a 3055 power transistor for output and a bit of circuit behind and
that is it, with radio shack round the corner you should be okay to make the thing cheaper. Good luck!!!!!

[caperren]

My original plan was to build the charging regulators myself, but the radioshack where I live is not stocked like most. They have a few small storage tubs with components, but they are unorganized and the parts I needed would have taken too long to get here before I needed the project done. Still, for the future, it's probably a good idea.

[Ernest12]

It isn't Radio Shack any more, it is now "The Shack" your cell phone source.
They have done as so many and forgot what built their business and what keeps their business alive. Cell phones won't cut it.

[Adlab]

Great idea, I love it! Do you put them in picnic / camping spots, so people can eat / rest while waiting for their gadgets to charge?
Also, do you ever have an issue with people turning up with a gadget and there being no juice left in the battery? Not sure how the sunlight / battery capactity balance works out...

[caperren]

They are on a campground, so day hikers, bikers, and overnight campers will all use the devices. I'm not sure about the second part as I haven't gotten feedback from the parks yet. Basically, I figure that the panel could charge one power hungry cellphone in full sunlight, so it is possible to run out of juice, once the battery dies....

[leifjohnston]

I would suggest these two projects are radically different. First this one is all DC and focused on USB outputs. Second the box etc is cheap.

A couple suggestions.

Mount the top at a degree measure equal to the latitude of the location, then point that south. That will optimize a non moveable solar array output.

Second, you should be able to drop the lighter sockets but wiring only the USB.

Finally, I would suggest using rechargeable NiCad batteries vs lead acid. As long as they are well maintained you can string them together and likely come up with a cheaper solution.

Also if you begin with aharbor fright solar system, you can likely cut out some components via scavenging.

Good idea to share power around.

[caperren]

I live at the 49th parallel and just made mine 45 degrees to make it simple. However, I did make sure to face them all south. I would have done usb only, but due to time constraints and the fact that I wanted at least on car light socket for those who had their own chargers, I decided against it.

[sammons]

Lead acid batteries are better suited to solar applications as they are much easier to keep charged as they no not mind being float charged, they actually prefer it. Ni-Cd's can exhibit a "memory effect" and can become damaged when improperly charged.

Wikipedia says "The primary trade-off with NiCd batteries is their higher cost and the use of cadmium. This heavy metal is an environmental hazard, and is highly toxic to all higher forms of life. NiCd batteries are also more costly than lead-acid batteries because nickel and cadmium are more costly materials."

Lead acid batteries are recyclable and are usually made from reclaimed lead.

Phil

[leifjohnston]

Toxicity isn't a key issue since lead is also toxic to most life forms.

But, my real point for considering NiCd rechargeables is that you can scale the size of storage easily and simply and generally for less. I can buy a 12 pack (1.5v and 1100 mAmphr each or 18V 13 amp hr combined) of cheap rechargeable NiCd for $6-10 where he was spending $18 for a single 12v 7amp hr lead acid, if I remember the facts correctly.

Additionally, a creative charge controller can push lower voltages into a serial connector and charge 1.5v batteries better than pushing to charge a 12v system.

Finally on the consumption side, since USB is pushing out at 5v, you could tune the system to use fewer NiCd and a lower voltage, likely cutting out components and wasted energy. Design might be impacted because it isn't the simpler 12v components but there are lots that work for 5v as well.

Just trying to offer and alternative vision. Yes lead take trickle charge better. Full discharge kills lead but not sure that is a risk. Nicad are likely going to get a memory over time, but that can be fixed with replacement.

There are always design trade offs, he had asked for other ideas. Since weight wasn't an issue, I didn't bring it up, but a traveling version of this would be significantly better.

[steppapajon]

Actually you would only have 14.4 volts and 1100 mAH with 12 NiCd batteries.
Each cell is 1.2 volts and if you place them in series you only add voltage not amps. For 18V and 13AH you would need 180 NiCds and that puts you in the $90.00-$150.00 range making an $18 SLA battery quite the bargain.

[sammons]

You have a good point. transforming 12DC to 5vDC has significant energy losses as the load increases. Hwvever 6v Pb Batteries exist, 6v solar panels exist and 6v solar charge controllers exist.

The solar Panel and Charge controller chosen here is 12v. For the project to use a 6v Ni-Cd battery pack, then an appropriate 6v Solar panel and 6v Charge controller capable of charging Ni-Cd's must be used. I would be interested if someone can give a link but I'm pretty sure standard solar charge controllers are only capable of charging Pb. So a modified battery charger of custom charger would have to be configured.