# Charging phones via solar battery chargers

For a school project, I want to make a solar iPhone charger (specifically for the iPhone 4) and I've spent about a week looking up stuff all over the Internet, and I'm stuck for the hundredth time. First, I had my mind set on an iPhone charger (if you're interested, it can be found here: http://www.instructables.com/id/Solar-7-up-Solar-phone-charger-in-a-bottle/%29) that basically uses a homemade 5V solar panel, which is plugged into a 3.7V 2000mAh LiPo battery, and then plugged into LiPo Rider Pro (which is apparently a lithium charge board that has a battery charge regulator and also steps up the voltage to 5V which is the required voltage for USBs). Anyways, a male to female USB cable is plugged into the LiPo Rider Pro and then you can use your iPhone USB charger to plug into the male to female USB cable to charge your phone via the LiPo battery (which is charged from the sun). I think this is how it goes... The instructable is unclear when it gets to plugging into the LiPo Rider Pro, and I've spent a long time trying to figure it out. (If anyone actually reads the instructable, feels that it's easy to explain the part about the LiPo Rider Pro, and feels inclined to do so, I would really appreciate it.)

Because of my uncertainty, I kept looking and came across another solar lithium battery iPhone charger (again, if interested: http://www.instructables.com/id/Lithium-Battery-Solar-USB-iPhone-Arduino-Charger/). I think it's very similar to the first one except this one uses a lithium battery charge controller and a DC-DC USB boosting circuit. My guess is that the LiPo Rider Pro is basically a board that includes both of these things? A 1N4001 diode is also used; use of the LiPo Rider Pro seems to make a diode unnecessary? What kind of confuses me is that the author of the first instructable calls the LiPo Rider Pro a "lithium charge board" and I kind of assumed that that's the same thing as a "lithium battery charge controller" which is used in this second instructable. The second one seems to have additional materials, and I'm unsure if that's better or worse.

So in sum, I guess my question is: what is "better", the LiPo Rider Pro (from the first instructable) or a lithium battery charge controller + a DC-DC USB boosting circuit + a 1N4001 diode (second instructable)? From my ignorant point of view, the LiPo Rider Pro seems better as it seems like an all-in-one. Yes, I've read both product descriptions, but I still don't really understand.

• From seeedstudio.com/wiki/… it shows three scenarios. Note, there is a battery on/off switch. It also says USB Mode: Solar Power charges lithium battery. Lithium battery supplies destination USB device And if you look at the schematic in Eagle, you will see that the solar panel output connects only to the charger ic. The battery connects to the regulator ic, through the on/off switch. – Passerby Mar 18 '13 at 0:16