Instructables
Picture of the
minisolarbook02.jpg
The "mini solar book" is another solar power supply and charger, which acts as LED light too.
Its torchlight function is very useful and effective. Indeed white LED only consumes 20 mA, so it will provide light for about 30 hours with a single charge of the battery, and with solar cells addition its life is practically endless. Of course you can also use this device to power your cellphone, your GPS logger, or any other little USB gadget (although battery has a reduced capacity due to its small size).

Step 1: The USB hub

To provide the connection to most devices is good to use an USB female socket. You can find many of them in USB hubs. This model has four USB 2.0 ports, you don't need 3.0 for this project, and actually 1.0 is good enough. 
Cut the circuit board in two and keep the smaller part with two USB sockets.
You can save remaining ports and USB plug for next projects.

Step 2: Solar cells and battery

Picture of solar cells and battery
minisolarbook05.jpg
I used very cheap 2V tiny solar cells. We need to obtain about 4-5V output voltage so let's connect two of them in series, indeed they will provide up to 5V in direct sun light, although the amperage will remain very low.
The battery is a small flat Li-ion 3.7V battery for cellphones, these are not powerful as 18650 cells but they are very small and a great choice for a project like this.
I opened the plastic case and extracted the Li-ion cell, with its protection circuit. Keep half case as cover and safe protection.
 
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stierney2 made it!2 months ago

Adding photos, I'm getting decent readings all the way to the USB port wires but when I plug in a USB cable - no charge. Maybe I soldered to the wrong spots?

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andrea biffi (author)  stierney22 months ago

it appears that you made a short circuit between the green wire and some other pins of the USB sockets...

I took an old USB cable and cut it - and made a test cable out of it - I reversed the polarity coming off the board, white should go where green is and green to white from mini board to usb board. I reversed these and I am getting a charge!!!! Pics added... hard to see but light on USB has power now where before it didn't

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Jan_Henrik5 months ago

Very cool!!!

andrea biffi (author)  Jan_Henrik2 months ago

thanks man!

siamex4 months ago

good job man this thing really helping me out keep up the good work.

andrea biffi (author)  siamex2 months ago

great!

stierney22 months ago

I made this Instructable (thank you for posting it) and I have some questions. I followed everything step-by-step but do not seem to be able to charge my phone with it. Now I will admit that it's been raining here and all but I was wondering - does the battery have to have a full charge before you can then charge other devices via the USB? I know my battery is good but dead at the moment.

andrea biffi (author)  stierney22 months ago

of course, charge the battery in the sun, for some hours. Then try to charge your phone.

Anyway new cellphones are very power-sucker (am I allowed to say that?) and those batteries are probably not powerful enough

Smatsh4 months ago

Hi!

A technical question : I have a 5V solar cell but they are "only" 250mA each. Can I connect them in parallel to increase the intensity ?

Very nice Instructable, simple and effective, the best :)

andrea biffi (author)  Smatsh4 months ago
yes you can, look my other solar instructable, I connected two and two in series and the two pairs in parallel, to reach double voltage and double intensity

Exact! Thanks for the answer :)

I love the idea of the pivots btw

I'll keep you update of my projet!

adnankhans4 months ago

hello Every One Can help me for make this circut or buy from any store Please Give me Links Or Help Me Make

Wow! Nice work! I could see this as a useful tool in many ways. How about a solar wallet?
andrea biffi (author)  KyleTheCreator5 months ago

then you need also a transparent pocket! ;-)

Flameofglory6 months ago

Thank you for showing me how to make this. I made a larger scale version to charger my airsoft batteries while I was on the field.

Thanks :)

andrea biffi (author)  Flameofglory5 months ago

I'm glad of that!

lukester297 months ago
I like your last solar charger but I love this one! Your really should sell this stuff because people like me define tilt would
andrea biffi (author)  lukester297 months ago

thanks! do you think people would like more to buy a kit ready to build or a gadget ready to use?

you can sell both. Many people want to build there own, but hate the time and confusion of sourcing all the apropriate parts. There are also many people that just want a finished gadget.

andrea biffi (author)  thedustycelt7 months ago

you are right.. I will plan to collect some kits and assemble some devices... maybe a kickstarter could help..

very beautiful idea!! congratulations andrea

hunter9997 months ago

Wow, this is a ingenious idea! This could be so handy 'cause of its size. There are a lot of possibilities for this, awesome job! :-)

andrea biffi (author)  hunter9997 months ago

thanks my friend!

astral_mage7 months ago

try going to dx.com or club.dx.com 4 yr charging usb gear.