How 2.0: Make a Solar Cell Phone Charger

From http://www.2pointhome.com

A little soldering is all it takes to make this cool little emergency cell phone charger. Keep it in the glove box of your car, in case you ever get stranded in the woods and start to hear banjo music!

You might be able to find the mini solar panels at a store that sells science or electronics equipment; otherwise you can order them online. Please note, you'll also be cutting the wire on the cell phone charger, so make sure it's not the only one you have! You can often find cheap chargers at discount stores like Big Lots -- it doesn't matter if it's AC or car compatible, since you'll only be using the end that plugs in your phone.

MATERIALS:

1 Altoids Tin case
2 Mini Solar Panels (3V 20mA each)
1 Solder (3")
1 Small Heat Shrink Tubing (4")
1 Large Heat Shrink Tubing (4")
1 Double Sided Tape (3")
1oz Flux
1 Solder Iron
1 Heat Gun
1 Wire Stripper
1 cell phone charger

Step 1 Step1: Cut wires & tubing

Take the 2 solar power panels and cut all four wires to about 1" in length. Cut 1/4" of plastic off of the tip of each wire with the wire stripper so copper wires are exposed. This exposed wire is called a 'lead.' Cut the small heat shrink tubing into four equal pieces (1" each). Slide the small heat shrink tubing onto both black wires.

Comments

[vandejake]

The circuit works just fine on all my tach toys, Fascinate 3G+ phone, Tabb the black berry playbook, basically anything with the micro USB, I would suggest (if you have multiple or different plugs-ins) adding male and female connectors, use some electronics lube so you don't create any resistance,
forget about overcharging even older phones will just run off the extra power once the battery is fully charged as if plugged into the wall.
awesome project
vandejake CET EET

[Pranjal Joshi]

Does it needs to add diode in circuit to prevent back flow of current?

[KETZ]

can i do it for my science fair ?????????

[jeyaram]

i cant imagine that i could do solar battery charger!!!

[yanacaballero]

yeah. how do we prevent it from overcharging?

[deathpod]

can a led work in place of a more orthodox diode?

[mike_k11]

But if i put a multi charger instead of  my cell phone cable ?...how can i chose a time 1/2, 1 or 2 hours switch ? and nothing else

Thanx

[Rick_Covert]

A polarity protecting diode should be a MUST when working with a project of this type for safety reasons and to protect the phone. Everyone makes mistakes and it would be tragic to loose a free or $40 pluse phone over something as careless as reversing the polarity of an under $10 solar charger. However the other posters have made valid points about the rather harsh voltage drop of .7 volts for using these diodes. Therefore I recommend the use of Schottky diodes which only exact a .2 volt drop penalty for their use.  A 1N5820, 1N5821 or 1N5822 should be more than sufficient for these needs and would only cost a .2 volt drop. I've used them in voltage regulation applications with an LM-315T voltage regulator where my source voltage was 12 volts and I was trying to get 9 volts out. A .7 volt drop is significant in this application and that's why I reached for the Schottky diode.

[Rick_Covert]

Sorry I meant to say that I used an LM-317T voltage regulator.

[emerson.john]

Do not put a diode in it. It will only cause the voltage available from that tiny solar array to drop .7V, and will thus degrade charging performance. Try to rember not to connect anything backwards and there is no reason for the diode. There is certainly no way it can IMPROVE performance.

[kpdyer]

hey, i did this but modified it a bit. The power is going through but the phone (an old Nokia 2610) won't charge, no matter how long I leave it up. what is happening???

[sharlston]

a diode is he answer

[sharlston]

hey i would insert a diode in there

[Colonel88]

Some phones will not charge because they are "stupid" Like u cannot just hookip a 5 volt regulator (7805) to a 9 volt battery and charge the itouch. It doesnt work and oh please put a diode on this or the charger will suck badly. :DD

[soapsayhello]

I am in China. Please email me soapsayhello@hotmail for solar cell phone chargers.

[reno91]

where do i get tha stuff

[11avumkh]

hey people out there i need a lil help with a something something im in Cape Town, South African and i need to find out where to buy the materials for a solar powered phone charger Do answer Shot ; - )

[imakethings]

did u add a diode?

[beayayan]

hey guys... i need your help i have a thesis proposal regarding in this topic "solar charger. email me at [e-mail] if you have any suggestion. thanks it will be big previleges to me

[gentlehorse]

Hi, your cell phone charger is cool. Is there anything to prevent the phone from overcharging? Thanks, Doug

[Briguy9]

you might have an old junky phone. Most new ones have sensors that sense when the battery is full and stops taking electricity from the power source, even though its still plugged in.

[kpdyer]

hey i'm doing a science fair project involving solar charging a cell phone and i saw this... would you mind if i based it on this instuctable and others like it? Also, about how much would it cost, and do you recommend any other instructables?

[Noname23]

Deliverance, nice. XD

[giloray]

woah........this is so cool..but how much is the total cost of the equipments that are used is making the device?... can anyone there help me in finding some research/....

[guitarmansmitty]

Sorry but I need to ask if anyone has actually done this one yet. The reason I ask is that I don't want to fry my battery and have to get another one (if I can even find one).

[Heavy Metal Handyman]

Dude I built the thing and had to make about 50 of em and let me tell you that solar cells VARY ALOT. Not one of the 100 solar cells was exact as per the specks (I painfully checked each one with my meter a very slow process indeed). I would suggest in purchasing 4 or 5 solar cells and take the highest voltage of the bunch and pair them together, thats what I did. I had no problem with the voltage being too high because of the low amperage. 7 and 8 volts was optimum for charging a dead cell phone. The ones I build for this demonstration worked but the sun must be bright. Again some worked better do to the large variation in solar cells strength. Lesson learned, ALL SOLAR CELLS ARE NOT CREATED EQAUL. No voltage regulator is required as far as the ones I built. Keep in mind the price you pay for something, 2 solar cells = 16.50 altoids tin 1.50 = $18.00 thats not including all the tape and solder and heatsrink tubing .....when you can already buy on the market wink wink for say $19.00.

[alex-sharetskiy]

put solar panels on both sides of the altoids tin, (on the inside) you might also want to add a voltage regulator so you don't kill your phone

[Nirjuana]

Probably regulator wouldn't work because they usually need about +2 volts larger input voltage than the output voltage. Simple voltage divider would work but it decreases efficiency. And I'm not even sure can you charge your phone with 30 mAh current...

[Nirjuana]

Sorry, I meant 20 mAh current.

[alex-sharetskiy]

the voltage regulators that i have, they would work, if you put 4 volts through them, you would get 3.5+/- volts out using a 5v regulator you probably could charge your phone, but the power you put into it, would be eaten by the phone's "check for signal" thing, so you might have to turn your phone off in order to charge it

[Nirjuana]

At least my charger gives out 5 volt so I'm no sure could it be run with anything below it. But I recommend to get some better solar cells, for example, you can get solar cells from DealExtreme that give out 80mAh @ 4V for 8.25$. And they're not even so big, 2.36 in x 2.36 in so it could be used for many purposes.

[jillg]

this is cool I've always liked solar powered gadgets oh also... First (always wanted to say that!)