i need help please, with solar cells! please please :)

i need to charge my iphone on the go, i have solar cells in an array to total up 4.5 volts, i have a diode ( black, gray stripe on one end) connected to a female USB plug, the little iphone adapter puts out 5 volts, please help me if you can! thank you for your time!

Wesley6668 years ago
Ya, get a germanium diode with less voltage drop and get a better solar cell. If you can get bendable ones, get them and then mount them on your shirt or backpack so you can charge and go!
led235 (author) 8 years ago
thank you for all of your help!
Honus8 years ago
Many USB devices use the data lines on the USB plug to tell the device that it is connected to a charging source. I'm guessing that since it doesn't have any interaction on the data lines it won't charge. You need to have two 100k pullup resistors tied to the data lines- you might need to do a google search to see how to do this.

Your voltage might also be a bit low. If I remember correctly USB spec calls for at least 4.7v and if your cells add up to 4.5v and then the diode drops the voltage (usually up to .7v depending on the type of diode, some are less) you might not be providing enough voltage.

Most DIY solar iPod chargers I've seen use a higher voltage solar cell and then use a voltage regulator to drop the voltage to 5v. Have a look here:
http://www.reuk.co.uk/Solar-iPod-Charger.htm

I made mine a bit differently:
https://www.instructables.com/id/How-to-make-a-solar-iPodiPhone-charger-aka-Might/