Universal Solar Charger




This is a universal solar powered charger for those of you (myself included) with minimal electronic knowledge and even less money. You make it out of one of those cheap universal car adapters and you can still use it as such afterwords. You can even change the panel you use whenever you want!

Step 1: Materials Needed

Ever want to charge something like your cell phone, mp3 player or even your gameboy, but don't want to pay over $60 for those portable solar chargers? Well, this is the place to find out how to do it. The best thing about this charger, is that you don't have to permanently attach it to your panel allowing you to change panels whenever you want! This instructable cost me about $10 since I had most everything lying around, but if you bought everything new, it should run you about $20-$30.

First off, let's see exactly what you will need to get this project started.

1 - Solar panel (mine in the picture is a 5.5w panel. You can
get them at Canadian Tire for about $30 on sale
and you can even get them at Wal-Mart now for
about the same.)
1 - Universal DC (Can be bought at many places for about $10)
to DC Charger

1 - Quick Connect

Tools including solder, screwdrivers, soldering iron and shrink tubing if you want.

Step 2: Get Started!

First, open up the DC to DC charger. It is not uncommon for these to be held together with security screws, but that's not too big of a problem. You can buy security bits and drivers from most any local tool store (not hardware store) and they are usually pretty cheap.

Inside, we can see that there's not much too them. All we need here, though, are the positive and negative terminals. They are incredibly easy to find. Just follow the two wires coming from the shaft to the pcb. On this one, it's the blue wire (positive) and the black one (negative). Black is almost always negative, but if you are not sure, just look at where the wires lead to. The negative one will always attach to the springy pin thing at the top while the positives will go to the sides.

Step 3: Soldering

Now we solder on the quick connect. We use these quick connects so you can change panels quickly or take it on the go. You can buy one on its own, but since one panel usualy comes with a few different ones to choose from, I like to just cut one up that I don't need.

It's important to make sure that you connect properly. To do that, we need to find out which wire is positive and which is negative. There are a few ways. Usualy, the pos is white and the neg is black, if they are not marked, look for a white stripe on one of the wires, that one will be positive. If you're still not sure, you will have to plug it in to the solar panel, and use a multimeter on the bare wires.

Drill a small hole somewhere in the casing for the quick connect to come out of. If you don't want to drill a hole and don't mind if you can't use the charger for your car ever again, you can just exit the wire through the shaft.

Now, pull the wires through the hole and solder it together.

Step 4: Final Touches

Screw it back together and you're done! Simple, eh? Now you can connect any solar panel with a quick connect, choose the correct voltage and start charging! You can add whatever kind of ends you want now, USB, one for your DS or PSP, whatever! Here's some of the other ones that I have made. I added two quick connects to one so I can use teo panels at a time. You can also see that I've added AA battery holders. I leave, one in my car and charge up 2 AA's in about a day or my cell phone in a couple of hours. They're very handy tools to have. Just one bit of advice, make sure not to overcharge anything. While some electronics have built-in regulators to prevent overcharging, not all of them do. Most things should be okay to leave for a day or two. Just be sure to keep an eye on the state of charge.



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    20 Discussions

    Might be a good idea to put a blocking diode inline between the charging device, in case you forget to unhook the charging device from th8is setup when there is no solar panel output, IE, when the sun isn't present or it's too cloudy to get (sufficient charging) output current from your panels. Otherwise, you risk draining your battery!


    7 years ago on Step 2

    Are you sure about the positive, I thought that the centre terminal was a positve. Perhaps on your polarity revering model it was around the other way.

    1 reply

    Here in the US, a good place to get a 5w panel is harbor freight, or make your own by salvaging several dead old LED solar yard lights


    9 years ago on Step 4

    Good find with that car jack charger, I wonder how easy those are to come by.


    It's hard to tell from the photograph (all I can make out are a few resistors) but it looks like that adapter does not provide any regulation. If it is unregulated ( and the panel definitely is) it would be unwise to plug expensive electronics into it! Is there at least a diode in the circuit to prevent the device discharging via the solar panel when the sun goes in?

    3 replies

    that adapter does regulate the output voltage. It uses a lm317, which is a variable voltage regulator. The output voltage is set by 2 resistors. The switch on the adapter changes the resistor combination to give different output voltage values.

    Good point. I completly forgot to mention that. It shouldn't be a problem with most small electronics. The small amount of current that a 2 or 5 watt panel (the size that these are intended for) puts out makes it pretty hard to cause any real damage in a day or so of sun. I added to the end of the instructable to include this, though.


    11 years ago on Introduction

    A few quick comments: In step 2, it's pretty clear that the blue wire is negative, and black is positive. You're right that black is usually negative, but this appears to be an exception!

    Also: You should really avoid those trailer-style quick connectors. They make it extremely easy to blow things up, since they change polarity when you change sides. What I mean is this:

    Say you have a battery in a box, with a wire leading out of the box so you can charge it. On the wire you have a quick-connect, with a matching one on the solar panel. For this example, let's say that the battery's negative is on the exposed QC terminal, which mates with the solar panel's shrouded terminal. On the solar panel, then, positive is on the exposed terminal.

    Not too bad, until you accidentally plug two batteries together. Now you have negative to positive and positive to negative, a dead circular short, which will melt your connectors, catch your wiring on fire, detonate your batteries, and ruin your reputation!

    Consider a genderless connector like the AndersonAnderson Powerpole, which has become the standard in many DC-power applications for precisely this reason. The APP connector keeps its polarity when you change sides, so you can just plug all your batteries, chargers, solar panels, and loads together without worry. Positive is always positive, negative is always negative. You can probably find them at your local hobby store, since they're popular with R/C modelers, and any ham radio club will sing you their praises (and probably help you pick up some nice tooling for cheap).

    6 replies

    Reply 10 years ago on Introduction

    Anderson power plugs are not the standard. Deans plugs are the way to go.


    Reply 10 years ago on Introduction

    Dean's plugs are popular in R/C modeling, where gender-based connectors make sense, since you're either connecting a battery to a vehicle, or connecting a battery to a charger. But say you're connecting three solar panels, two batteries, a light, a fan, two radios, and a laptop charger. Which devices get which gender of connectors?

    That's precisely why Anderson Powerpoles are popular in amateur radio and other environments where things aren't always as simple as in an R/C model. Just throw a few pairs of connectors on everything, and plug it together however you like. Positive is always positive and negative is always negative, and there's no need for gender. Deans and JST connectors are great in some applications, but Powerpoles (also called Sermos connectors by some modelers) are more appropriate on solar panels, batteries, and power distribution applications.

    Anderson Powerpoles definitely are the standard in many applications. ARES/RACES have specified them as the official standard DC power connector for all their operations, and they're the de facto standard across all of amateur radio. For simple one-battery-one-device connections, the connector varies with the industry, but anywhere you find people doing complicated things with DC, you'll find Powerpoles.


    Reply 10 years ago on Introduction

    I just like deans plugs. I actually use a male XLR plug on the each solar panel and a female panel mount connector on my battery bow that connects to my solar charger. They work nice because they lock and don't look half bad.


    Reply 11 years ago on Introduction

    That's right, you can't always trust the colour of the wires, that's why I said to use a multimeter if you are not sure. On this particular model, however, it doesn't matter because there is a switch that allows you to choose the polarity you want on the side. The others that I made had those anderson connectors you mentioned.


    10 years ago on Introduction

    The tip of the plug is always posative and the sides are always negative


    11 years ago on Introduction

    i made a circuit i call a "cat,s bladder" it will help this out

    sorry for the gross name!


    11 years ago on Introduction

    sweet I'm gonna do this with a Ipod car charger.