Altoids USB Battery/Solar charger for iPhone and iPod

I know there are plenty of USB chargers out there for you to build.  But here's one that doesn't use a voltage regulator or an IC chip to power it.  The basic concept is to use 4 - AAA rechargeable batteries (1.2V a piece) to power the USB and a couple of solar cells to charge the batteries.  If you've done the basic math you're probably wondering how 4.8V (4 x 1.2) is going to power a USB device which requires 5VDC.  Well that's actually how I came up with the idea.  I have another charger I made using a 9V battery and a 5V regulator.  It will charge my iPod until the battery runs low.  When I test the voltage output at the USB with a spent 9V, it will be spitting out 4.7V.  So that's the cut off point.  4.8V is still within the tolerance for a USB device to charge.  So I tried a 4-cell setup on my breadboard and it worked!  I tested the voltage at the USB socket and (to my surprise) it was at 5.2V.  I put my voltmeter on each battery and they were cranking out 1.3V at full charge.  This is great!  The tolerance of a USB happens to be just right for these four cells.  So the solar part was sort of an afterthought for charging the batteries (they are rechargeable anyway).

If you'd like to try to make one yourself, here's what you need:

4 - AAA Battery Holder

USB Socket (female)

Solar Panel (3V output minimum, around 5V max)

Blocking Diode (not LED)

Some resistors (This is somewhat optional.  You need them if you want your iPod/iPhone to recognize your charger.  I'll explain exactly which ones to use later.)

DPDT Toggle Switch

Small Perf Board (Also optional)

Soldering Iron

Step 1: Prepare the tin

I started with an easy step.  Paint the tin.  I just wanted to start with a blank canvas.  You do too... trust me.

Comments

[kaylee_ct]

I have no idea what kind of "board" you're talking about. It is not mentioned in the materials list. I am just so confused right now. If anyone can help, it would be greatly appreciated.

[haikuordie]

The materials list has a "Small perf board". It's the type you can buy at places like Radio Shack. They typically call it a "project board" but it is often call a perferrated board. I said that it was optional because you can always solder the parts together without any board if you're a well-seasoned solderer. I don't suggest this BTW. I only put it out there because I've done this a great many times myself when I was in a pinch and just wanted to try out a circuit (I use a breadboard for such endeavers nowadays). I hope this isn't your first project. I know I've messed up many a component trying to do a project I wasn't ready for. Message me if you have any other questions.

myk

[pmvinuelas]

if you wanted to remove the batteries and have the solar panels directly charge your iphone, how big would you need the panels to be?

I am looking to have something that can charge my phone while i am outside but want it as small and light as possible. I figured if i removed the batteries i would just need to make sure i had enough power from the solar panels to come in and some sort of charge regulator right?

Thanks for the help.

[Anianna]

You may be more interested in a build entirely without batteries, then, such as:

http://www.instructables.com/id/Altoids-Smalls-Solar-Powered-USB-Charger/

[pooyathr]

It means that if we wana to charge an android device we don't need resestors?
Plz answer as soon as you can.

[haikuordie]

Yes. It means you don't need the resisters. Apple devices require voltage to the data pins but most others do not.

[mattglas]

Can you take a picture of the top part of the Pref board? If you can that world be awesome becaus ei am having trouble using the skematic

[Fashiondez]

I hooked mine up and the phone recognizes it is plugged in, but does not charge. Troubleshoot? Cut wires and re solder?

[jpman]

Hey cool instructable i finished mine today and tested it out on my brothers Black Berry it ended up Discharging the phones battery it went from 85% to 80% what do you think?? oh and i put a Blocking Doide before going to the USB on the lead

[Helpinghandsofhope]

Hello. I was wondering where you could find the colored data wires such as yellow , green,blue,dark blue, etc. I don't want to destroy my ipod charger to just get to the wires. The cord is $30 I'm sure your aware of the USB cables for iPods. Thanks help much appreciated.

[Helpinghandsofhope]

Also what gauges are the wires you used just wondering and what voltages or amps? Thanks again.

[haikuordie]

The wires I used were (I believe) 18 gauge. They may have been 20, but I don't have anymore wire left to check. I think I purchased a 100ft roll of "round wire" at a local electronic supplier (very much like Radio Shack, but cheaper) for around $5 USD. It's great for projects and fits beautifully into a breadboard. I wouldn't suggest cutting into your charge/sync cord.

If you're paying $30 for an iPod cord, you haven't looked around much. I get them online for about $2.

try here: http://www.miniinthebox.com/cables_c4611?keyword=ipod+cable

I still wouldn't cut it unless it was broken anyway. If you need a female usb I found them somewhere for around $.25 a piece (+ shipping)

[jpman]

Should i put a diode in the postive end of the battery? to prevent discharge from the usb?

[haikuordie]

I'm not sure what exactly you're asking. The schematic shows everything you will need. The only diode necessary is the one preventing the solar cells from drawing current from the batteries. If you're afraid the usb will draw a current on it's own, I don't think that is possible. The voltage dividers will draw a current while the charger is at rest (albeit a small one), a diode will not eliminate this problem. My suggestion would be to add a shut-off switch. Hope this helps.

[jpman]

cant i just get 2x double a holders and wire them in parallel?

[haikuordie]

Yes, you can. But if you still want to fit then into an Altoids tin, I'm sure you'll have some trouble.

[jpman]

Could i use 2 AA instead of 4 AAA's?

[Helpinghandsofhope]

Is it possible to make a how to video and post it on YouTube. I'm a amateur and not knowing much about soldering the right parts together. I don't understand the schematic real well. It would so kind if you can email me a video or send some closer photos of the soldering on the pref board. Please and thank you. My email is [e-mail]

[haikuordie]

I don't have enough time to make a video. I don't even have the time to make the other I'bles I've been working on. Sorry.

[Fashiondez]

i am building a usb solar charger and if i use a usb car charger's circuit board, and it doesn't have a + or -, is there any other way to tell where the positive and negatives are?

[haikuordie]

If what I am to assume is that you want to use a solar panel in place of the car battery for powering the charger circuit, than I would say it may not work for you. You need a solar panel that puts out at least 12vdc to be in place of a car's cigarette lighter socket.

But if that's the way you are going I would say the best way to tell which wire is + or - would be the color. Ground (or -) is usually black and + is usually red. If you saw where they came off the cigarette charger, the outside part is ground and the tip of the charger is +. If all else fails you can use the trial and error approach.

[Fashiondez]

Thank you! (yes, i have two 4.5v 80mA solar cells hooked up in what i believe is a series and those are connected to two AAs which are all then connected to the usb circuit board.)
I think that is about right. A BLACK WIRE came off of the SIDE of the board near the back (cigarette lighter end) and there was a METAL ROD that came off of the CENTER of that end (it is right after a resistor...i think...if those are labeled "R" 1) and that one was connected to a spring that was sticking out from the board. Any help is appreciated. If not, that's ok. Thanks

[haikuordie]

Two 4.5vdc cells will only add up to 9v. If that circuit was intended to run off a cigarette lighter than it will require 12v. If you know something I don't about the circuit you're using than that's fine. If those cells are going to be for charging the AAs than they are too much in series.

The black wire should be ground. The other wire is then positive. That is most likely a fuse and not a resistor between the tip and the spring.

[Fashiondez]

I should thank you for pointing that out. You are right. So is it better to change the solar cells or the circuit board?

[haikuordie]

I would suggest going with whatever you feel more comfortable with. You could use the solar cells in the design I've laid out. In this case I would attach them in parallel rather than series.
Or you could just use the already-made circuit board with enough solar cells to power it. You would need another 4.5v solar cell in the series to do this. (13.5v total would not be enough to damage the circuit by the way). If your intention is to have the solar cells charge batteries that will operate the circuit than you can just adapt my design.
I hope this helped.

--- myk
[e-mail]

[Fashiondez]

Thank you!

[dereklevine158]

i keep doing the same damn thing and my batteries heat up and my phone doent charge im using a max 6 volt solar panel

[haikuordie]

I have no way of diagnosing the problem if I can't see what you did. If you have any questions as to my instructions, feel free to ask. It sounds to me like you need a good multimeter to figure out what's going wrong.

[super knex builder]

so, what kind of resister does it need?

[haikuordie]

You'll have to be a little more specific.

[super knex builder]

in the beginning of the instructable, said, ' Some resistors (This is somewhat optional. You need them if you want your iPod/iPhone to recognize your charger. I'll explain exactly which ones to use later.)' but then never explaned what to use. if i just missed it, couldd some one point it out? and if its not their , could someone s

[haikuordie]

I explained in step five which ones I used. If you are still unclear as to what to use and why, you can shoot me an email.

[super knex builder]

nope, that's it. thanks.

[marianoargueta]

can we use a AA holder?

[haikuordie]

Of course... If it fits into your project box. The AAA fits snugly enough into an Altoids can with sufficient room for the rest of the components.

[Bantri]

I too would also like to know how to add the LED light, and also, how would I include a master on/off switch? And what kind of blocking diode do I need?

[haikuordie]

This should help,

[haikuordie]

If you want the LED for an indicator light, just wire it in line with a resistor to match the voltage from the batteries. The value of the resistor depends on the voltage required for the LED that you choose to use. I can't remember the formula but it's just as easy to use a potentiometer and multimeter to figure it out.

The blocking diode is really your choice. I would suggest using a germanium or Schottky diode because they have a low voltage drop. Any diode will do besides an LED.

[NSheneman3]

What do I do to the switch if I am using a 6v solar panel and 1 battery pack that holds 4 batteries?

[haikuordie]

You can skip the DPDT switch if you have enough voltage from your solar panel to charge all of your batteries at once.