How I built a Solar iPhone Charger for under $50.

Step 6 Conclusion

In future designs, I'll definitely be adding a battery so that you can charge your devices at a more convenient time. I'd also like to make a more portable version of this charger. With all of the new solar technology, flexible panels are bound to cheapen up sometime!

If you have any questions, please leave them in a comment.

Thanks!

Brennan

Comments

[Asmodeo]

Nice instructable!
I was thinking about something like this to recharge my cellular phone....
The regulator goes "hot" because the formula to calculate the disipated power is:

P=(Vin - Vout) / Iout
In your circuit:
P = (20v - 5v) / 0.5A = 15v / 0.5A = 30Watts!!!

Go get a heathsink for your poor regulator!

You possibly could use a 12V solar panel, with 0.5 Amperes output current, and the dissipated power would be

( 12v - 5v ) / 0.5A = 14W ...still in need of a heathsink...

I don't know if there are 9v solar panels.....

[solaralternatives]

Wrong. P=IE, not P=I/E, so P out(max) is 7.5W

[bananafred]

Just so you know, 15v at 0.5A is 7.5W, not 30. You multiply, not divide.

[Asmodeo]

OUCH! YES, you´r right!!! but....I made you think. huh!

[DraakUSA]

You should have spotted that since it's only a 10W solar panel. ;-)

[lloydrmc]

Darn, I thought that he had cold fusion or something going there.

[akbrennan]

Yes it is! I wondered where he was getting 30W, from calculation of a 10W panel... Thanks for pointing that out! Brennan

[ctfjustice]

Sorry, I forgot to mention that it has several different settings for different voltages. They are as follows, 3, 6, 9, 12 volt configurations. I got it just to tinker with, works pretty well for my purpose and curiousity.

[ctfjustice]

Hello Asmodeo, just a quick little blurp about you wondering if there were any 9 volt solar panels out there. Harbour Freight sells a neat little solar charger with battery power as well for around $12, not bad.

[DarkStarPDX]

Yo! I just picked up the "1.5 Watt Solar Panel w/Auto Lighter Adaptor" from a Harbor Freight store for $14.99. My plan is to build a USB charger as well, however I'm going to desulfate a 12 volt hobby battery (7 amp hour) and use that to capture the daytime sun, and then charge my USB devices at night.

After I make my prototype, hopefully I'll buy another to put together an instructable, but a sneak preview includes me using 5 volt switching regulators instead of 7805's (linear regulators). You can get the switching regulators from Dimension Engineering. Another problem I need to work around is moving the solar panel "smarts" from the "auto lighter adapter" to the inside of the actual solar panel.

Lookin' great, keep it up!

[lloydrmc]

Mouser.com has the Murata switch mode regulator

[akbrennan]

Thanks guys! @Asmodeo - There are 9V panels. However, this was the best one that I could find for the price. As I mentioned, it's certainly not the most ideal for charging via USB, most likely it was made for charging 12V batteries. I was considering building my own custom panel, which would be the most efficient - but this was the easiest and fastest method, which makes for a good instructable for beginners. I'll continue to document my projects. Thanks for your comments!

[monkyDJ]

I hope this works man, because I doing this for a project and I need to get a good mark!!! lolz

[krimb1]

 What a great guide! Really sturdy, and the built-in blocking diode is really awesome.

One question though: this setup won't trickle charge the iPhone after it's fully charged, right?

[lloydrmc]

I seriously doubt that an iPhone counts on the charger to do anything. The charge circuitry is going to be in the phone.

[mediaburn]

So what type of charge times are you getting with this set up?

[akbrennan]

In full sun, the amperage is exactly what a computer USB port puts out. ' The charge time will depend on the solar insolation, but if you have good sunlight - about the same amount of time it takes to charge when it's plugged into your computer.

[p0g068]

thank you ! nice and clear cant wait for the upgrade to using a battery!