Introduction: Cheap Solar 5 Volt Charger/ Power Supply

Picture of Cheap Solar 5 Volt Charger/ Power Supply

In this instructable I used 5 CHEAP solar lights. As I recall I bought them for $2 each at Wal*Mart over a year ago.
It would be hard to find the solar cells for that price let alone the whole light assembly etc.

Step 1: Let's Get Started

Picture of Let's Get Started

First I headed to the DOLLAR TREE dollar store where everything is a dollar, not $1,2,3.50 etc.

I was searching for a container that was in the experimenters budget along with one that had some qualities I was looking for.
this box has a 4 side snap feature. It is easy open/ easy close etc. The one thing I liked is the rubber seal built in the lid portion.
This should make things fairly water tight.

 I may use this during emergency situations (preparedness). As a Ham Radio operator I need to be prepared to work emergency communications at some point.  A solar charger for a cell phone or other device would be handy.

Step 2: Preparing the Cell/battery Combination

Picture of Preparing the Cell/battery Combination

As you can see these lights were part of a July 4th celebration and thus they sold cheap the day after on clearance. you will notice I took a black sharpie marker and blotted out the stars on the side of the casings. Not that I am not patriotic but isn't the focus of this instructable.


The underside/base has three screws that need to be removed. I cut the RED and BLACK wires (positive and negative) on both the battery and solar cell right where they connect to the circuit board.

I am not one to throw things a way but in this case I tossed the circuit board and light assembly I have too much of this stuff hanging around :)

After the light assembly was removed I turned the cell upside down. I used a sharp paring knife to strip the wires about 1/3-1/2 inch long.  BE CAREFUL  KNIVES ARE SHARP!!!


You will want to join both red wires together as both black wires.  this creates a parallel circuit between the solar cell and the Ni-Cad battery.

I created an extra red wire that I used to bridge from cell to cell thus allowing me to move and locate the cells in the box at will.

Step 3: Assembly

Picture of Assembly

In this picture you can see the 5 cells soldered  positive to negative in a series circuit.

Each battery is what is known as a 2/3 AA cell. They are 1.2 volts when charged. We should show a voltage of aproximately 6 volts or more.  As you can see I had 6.25 volts with out the circuit loaded.

This voltage will give us enough voltage to regulate it down to somewhere between 4.8 and 5.2 volts. Most 5 volt devices charge at about 5 to 5.2 volts.

As some of you know a Zener diode can reduce the circuit voltage by .5 to 1 volt  if placed in the circuit.

The second picture shows the zener diodes that I used. They show a voltage drop of about 1/2 volt each.

Using a voltage regulator such as a LM317 would be counter productive as losses would be too great.

I put 2 diodes in series and obtained approximately a 1 volt drop just what I was looking for.

As you can see the meter is reading 5.11 volts un-loaded, this should work very well.

My guess is that it will take a bit of time to charge a phone due to low amperage.

Step 4: Wire Assembly

Picture of Wire Assembly

Here you can see all 5 cells in the container sitting loosely.

I chose to use a female USB cord end for connection.
The second picture shows the wiring of the USB cable. The red and black are obviously positive and negative. The green and white wires are not used. The green and white wires are for data transfer in a computer context.

I poked a hole in the side of the container end. After knotting and feeding the USB line through the side I tied another knot to secure it somewhat.

By using the female USB cord you can switch out all manner of other 5 volt accessory cords for different devices.

I will most likely use some clear silicone around the cable entry to as to keep it moisture resistant in bad climates.

Step 5: Securing the Components

Picture of Securing the Components

I believe a picture is definately worth a thousand words.

I hope the 6 pictures are of some assistance in knowing what I did to secure the solar cells in the container.

All I can say is that hot glue is my friend. I personally would use nothing else in this case. The time and frustration of other glues would be too much hassle.

You will notice I also attached the two zener diodes to the side of the center cell casing. I also used about one drop of glue per solder junction after carefully trimming the excess wire..
The hot glue really helps to secure the junctions on these very thin wires. Who knows how much rough use t his charger could get. Possibly tossed around a bit ?

Step 6: The Final Results

Picture of The Final Results

I was testing things out and realized I had glued the junction beyond the last diode  :((
I had to do my voltage test at the center of the two diodes then subtract .5 volts for the last diode.

Basically I ended up with 5.09 volts DC. 

You will see the micro USB charge cord from my cell phone. I was tired and thought I would hook up the phone and take a picture of it charging... YEAH RIGHT!  It's hard to take a picture of a phone charging when you are using the same phone to take the pictures.

Time to go to sleep Bryan!!!!

I took 3 pictures of the container/enclosure so that you could see the seal and side lock assembly. 

On the theoretical TOP/LID of the container I am going to hot glue some sort of non slip material. My hope is to be able to set this in a window sill, a dashboard of a vehicle, a picnic table and know that it won't slide off for any reason.


******* JUST A CONSTRUCTION NOTE *******

You might remember to have a moist (More wet than dry)  sponge handy for the hot glue work.
First off hot glue is dangerous if handled carelessly.

CHILDREN SHOULD NEVER USE HOT GLUE UN-ASSISTED !!!

** When attaching the cell to the container I suggest this to make it easier.
be careful about getting hot glue over the solar cells. I doubt the glue would harm them but it would look messy.

After you squirt glue around the cell keep your finger on the shell of the cell/battery combo to keep it in position. then lift the container and set it on the moist sponge to absorb the excess heat from the glued union.

This cools things down safely and allows you to move forward quicker with out components accidently shifting out of place.

I hope you have received some creative ideas for your next project.

Enjoy!

Comments

MuhammadK18 (author)2015-08-30

! bought 2 solar garden lights for a £1. Unfortunately they r just 40mA, 1.2V each so i guess I need 5 of them in series to make it 6V and 15 of them parallel to make just 520mA so i guess i should go for a £5 solar chager with 700-800 mAh and 5V.

TechMechgames (author)2015-05-27

to make this MUCH smaller, I took the actual solar panel out of the case, it was basically a square piece of glass that made electricity.

SOMUAK (author)2015-04-06

I PURCHASED MINI SOLAR PANEL PL SEND FURTHER DETAILS MY MAIL ID somuakbsnl@gmail.com

cwolfe13 (author)2014-11-16

I made this a while back as a camping phone charger the dollar tree now sell these lights and they come with rechagable AAA batteries if you use a hair dryer or a heat gun on low you can soften the hot glue used to keep the panels in place and take them out of the cap. I love these lights and buy as many as I can since now for a dollar I get a solar panel a rechargeable AAA an led a ground stake and a cool project tube if your dollar tree has them in stock buy them all unless your in a town called killeen then back off there all mine lol

kc8hps (author)cwolfe132014-11-16

If you get time please take a picture of how you did your solar project and posted It id really like to see how you did it thank you.

litchex (author)2014-10-12

i love it :D

shellrose_2000 (author)2013-08-28

Love this instructable. I am just a little confused on the wiring. Do the diodes just connect the negative wires together and you connect that to the usb, and you keep all the red wires connected in a string?

tigers58 (author)2013-02-19

Great instructable! Thanks for posting it. I agree with Manuka, a circuit diagram would really be helpful. It is very difficult to see from the photos where the diodes are connected, and their polarity.

JerryBYong (author)2013-01-30

Hi, does this work with the iPhone?

jukees (author)2012-11-01

nice instructable, not so handy to those who don't have access to wal-mart, but solar garden lights are pretty much the same.
and i didn't know about the zeners dropping the voltage, thank you.

Schmidty16 (author)2012-09-26

hey uo the only thing i would change is adding black paper or card board arount the solar pannels to get more eletricty

bllwdcrvr (author)2012-09-02

yes I found the same yard stake light for 97Cents each today..so I grabbed up 5 of them..yes they make a great little rechargeable flashlight..

MarkinDetroit (author)2012-09-02

I saw the same style lights on sale for $2 each and thought the same thing... where else could I get a solar cell, battery and LED for that price!
Without gutting them, they make great little flashlights. I also thought about separating the solar cells from the housing and mounting the lights under the kitchen cabinets and wiring the solar cells to a nearby window.
This is a great idea too, love the $1 store box to package the whole thing.

manuka (author)2012-09-01

Bravo!  SGL (Solar Garden Lamps) certainly make VERY cost effective  "engines"- I've used them extensively for all manner of projects => https://www.instructables.com/id/Education-Solar-Garden-Lamp-based-pendant/  They make a good source of parts too, perhaps just for the low voltage drop Schottky Diodes ( which are never in a junk box when needed!)

You really should include a circuit diagramhowever, as folks may be confused about connections without it. In fact I was initially unsure if those batteries were totally bypassed! It's worth stressing the merits of leaving them in circuit to charge up by day (when you'll be out with your cell phone anyway), then plug in the phone for night charging from the batteries.

FWIW -each PV slice typically produces ½ V ( thus 4 x ½ =2V) at 10mA, making the bare cells handy for powering small devices ( tiny motors,red LEDs etc).  However the  "quadistor" (ZE002) electronics in most produce spiked boosted voltages (~ 5V ) but at low currents ( <10mA), which is enough to light a white LED, and also alone may have some cell phone charging mileage !  See => https://www.instructables.com/image/F4MAL5MGSEEK0QH

Stan.

aaahotdog (author)2012-08-27

One thing that needs to be checked is voltage under load. You might get 5.1v with no load, but when there is a load, what happens to output? This might be more viable as a power source rather than a charger. Nice design though.

rimar2000 (author)2012-08-26

This is very useful, thanks for sharing.

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