What do these 2 items have in common? Well you might carry them together in a purse or backpack. By the end of this instructable they will have a lot in Common.
I'm gonna show you how to take the guts from an old LED landscape light and make it into a portable phone charger. HERES THE DISCLAMER " I HAVE NO IDEA HOW ALL BRANDS OF CELL PHONES WORK AND I"M NOT AN ELECTRICIAN SO TRY NOT TO KILL YOU NEW $400 PHONE. I JUST KNOW IT WORKED ON MINE"
I'm gonna show you how to take the guts from an old LED landscape light and make it into a portable phone charger. HERES THE DISCLAMER " I HAVE NO IDEA HOW ALL BRANDS OF CELL PHONES WORK AND I"M NOT AN ELECTRICIAN SO TRY NOT TO KILL YOU NEW $400 PHONE. I JUST KNOW IT WORKED ON MINE"
Step 1: Stuff you will need for your Solar Cell Phone Charger
First you will need..
Altoids tin (empty)
Solar Cell small 6 v 3 1/4" x 2" or smaller
(I used the guts out of a cheap landscaping LED light. If you can find one that doesn't work its prob the battery, and we don't need them)
NOTE: I'm not electrical genius but every cell phone I have had in the last few years has a 3.7v lion battery. The wall charger I have for my phone now puts out 5.7v and so does the solar cell??? So I'm guessing that any solar cell 3v to 6v might work. My old wall charger works for my phone and it's out put is 3.7v. I have tested little solar cells in the sun and 3v cells will put out 4v easy. If you read the back of your wall charger and find out what the output is and match that to a solar cell you should be in business.
Electrical tape
Velcro (with the stick back)
Plug in charger (that fits in your phone an old one car or wall)
Soldering Iron (solder)
Voltage Meter (If you know how to use it ..or you can wing it and maybe blow up your phone)
Hack Saw Blade
Altoids tin (empty)
Solar Cell small 6 v 3 1/4" x 2" or smaller
(I used the guts out of a cheap landscaping LED light. If you can find one that doesn't work its prob the battery, and we don't need them)
NOTE: I'm not electrical genius but every cell phone I have had in the last few years has a 3.7v lion battery. The wall charger I have for my phone now puts out 5.7v and so does the solar cell??? So I'm guessing that any solar cell 3v to 6v might work. My old wall charger works for my phone and it's out put is 3.7v. I have tested little solar cells in the sun and 3v cells will put out 4v easy. If you read the back of your wall charger and find out what the output is and match that to a solar cell you should be in business.
Electrical tape
Velcro (with the stick back)
Plug in charger (that fits in your phone an old one car or wall)
Soldering Iron (solder)
Voltage Meter (If you know how to use it ..or you can wing it and maybe blow up your phone)
Hack Saw Blade
Step 2: Prep the Solar Cell and other stuff
I got mine out of a broken land scape LED light. The kind you poke in the ground and use to light the path. Once I got it free of the plastic shell. I cut the solar cell free of the battery and the circuit board. Then I used a hack saw blade to cut some old plastic bits off the back of the plastic mounting board the solar cells are attached to so it will be flat.
I check the cell (in the sun light) for polarity that means which contact is + and - (if you don't know how to use a voltage meter search the ALL KNOWING INTER-WEB)
I also checked the polarity of the plugged in charger I marked the + wire with tape. Then I cut the wire in half. We only want the side that goes in the cell phone.
I check the cell (in the sun light) for polarity that means which contact is + and - (if you don't know how to use a voltage meter search the ALL KNOWING INTER-WEB)
I also checked the polarity of the plugged in charger I marked the + wire with tape. Then I cut the wire in half. We only want the side that goes in the cell phone.
Step 3: Prep the Altoids tin
I put some electrical tape on the inside of the tin to protect against possible shorts.
Next I soldered the charger wires to the solar cell + to + and - to -.
Next I soldered the charger wires to the solar cell + to + and - to -.
Step 4: Attach the solar cell to the lid
I used some sticky sided Velcro and stuck one piece to the center of the solar cell and one to the center of the lid. I also covered the exposed wire and contacts with some electrical tape.
Step 5: I think your done
Stick the solar cell in the lid, plug in your cell phone and point it at the sun.
You can now toss it in your bag and forget about it. Just remember about it when your almost out of juice and need to make some calls. I found I can even charge it under strong indoor lighting.
You can now toss it in your bag and forget about it. Just remember about it when your almost out of juice and need to make some calls. I found I can even charge it under strong indoor lighting.
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mA (milliamps), Amps, etc. are a measure of current. Current is the amount of charge flowing through a certain point.
Volts are a measure of voltage (which has a bunch of other names, but we won't get into that). Voltage is related to the energy given to each charge.
We can use an analogy to water here, at least at this level. We can think of electric current as water current, and we can think of voltage as the height of the water above the ground. Charge (and current) will want to flow from high voltage to low voltage, like water would want to flow from high ground to low ground.
So the solar cell needs to have a higher voltage than the battery it is charging so that current goes into the battery instead of out of it.
Some people have mentioned an electronic device called a diode. A diode only allows current to go in one direction. Putting some of these in the right places will make sure that no current (and no energy) goes out of the battery when the solar cell is moved out of the light. I would have to research solar cells before I could say whether a diode is truly necessary here. It is possible that it would not take much current to raise the voltage of the solar cell to that of the battery. (Think about filling a tube with water; if it is skinny and water does not leave, it won't take much water. If there is a hole in the tube or it is really wide, it will take a lot of water.)
I think that I should also mention power, because nobody else has. Power is measured in Watts. If you multiply power x time, you get energy. On electric bills, they charge you for energy in terms of kilowatt x hours (where a kiloatt is 1000 Watts).
Power (in Watts) = voltage (in volts) x current (in Amps)
There are 1000 mA in one Amp.
The nokia 6300.
It is not likely you will build this to 850ma using a pair of lawnscaping panels... but worry not, you do not need anywhere near 850ma if you are patient.
There could be a low-current cutoff in your phone - say 200ma (just a guess) under which the phone will not charge. I think phones with smaller batteries can get by on less charge, whereas something like a droid or iphone would be more picky.
If your cells can not maintain 5v reliably, you will want to run your power (whatever you get) through a MintyBoost circuit.
The Minty design is now at v3, but a Minty v2 (I think there is a tutorial here) would be more efficient for this application, and you can get the MAX756 chip sampled free. :-)
.. and if it does not work with your phone no matter what, use the cells to charge a NiMH AA batteries which are pretty forgiving. Then use the AA batteries to charge your phone (4 rechargable AA's directly will charge your phone, or 2-4 rechargable AA's through a MintyBoost will give you a nice flat 5V output curve until the batteries are completely empty).
Personally, I would not buy landscape lights to try this out. If you have some already, great. If you are going to buy something, I would go for one of the newer better solar cells from Adafruit or Sparkfun, etc.