I found a guide online that shows how to make a solar phone charger (in a bottle), and I thought I'd try it out, but I'm worried about damaging my iPhone 4 (for a school project).
(If anyone's interested, it's found here: http://www.instructables.com/id/Solar-7-up-Solar-phone-charger-in-a-bottle/#intro)
But basically you use small pieces of solar cells (the author of the guide calls them "solettes") and superglue them together in series (so it's not exactly a solar panel; it does what you need though). 11 solettes are needed.
I purchased them on eBay as 52x19mm solar cells; the seller gave the following information for each:
Average Power (Watts): 0.14 Wp
Average Current (Amps): 0.28 Imax
Average Voltage (Volts): 0.5 Vmax
Everywhere I looked said iPhones need 5V since it uses a USB charger, so as the guide says, you'd need ten 0.5V solettes, plus one " 'false' solette that doesn't produce electricity but just serves to bring do the top surface connections to a solette underbelly". To my understanding, amps and watts don't really matter, the volts do (I think higher amps/watts just mean it would charge faster)? I'm really new to all of this.
Anyway, the voltage will probably differ a bit from the required 5V and also the amount of sunshine you'd get would change things a lot, so I was wondering if getting the wrong amount of voltage (and oftentimes - when the sun isn't shining - less voltage) could damage my phone.
A lithium battery and a lithium charge chip or board is also needed. The author used a 2000mAh LiPo. The guide says:
In order to power the LiPo charge circuit, which then pumps current into the LiPo battery, which then charges your smartphone, we need to produce 4.8V - 6VDC from our homemade solar panel.
I was wondering if it was possible for someone to explain this part a bit. The cheapest rechargeable 2000mAh LiPo battery on eBay is a 3.7V one (others have 11.1V, others have 7.4V, etc). Can I use any kind of battery? And what I don't understand is if the battery has its own voltage then isn't the amount of volts that goes to the phone 3.7V (from the battery) rather than 5V (from the solar panel)? I'm sorry if this is a stupid question, even a link or something would be sufficient, I couldn't find an explanation online myself.