Thank you adafruit!
In essence, it is the internal lithium polymer (LIpo) battery that, once it is charged enough to its nominal 3.7V, trickle charges the phone. But is that trickle charging in that case or can we call it regular charging at a slow rate? Maybe a cell phone always trickle charge once its total charge is high enough...
If we had more solar cells connected in series, then we could get a voltage high enough for the booster to convert it to 5V, correct?
Does the Iphone really need 5V AND 500 mA? What if we provided it with 5V and 200 mA? Would we still be able to trickle charge the phone?
But, I guess, that would not happen because if the load (phone) gets 5V, automatically its internal impedance makes it draw exactly 500 mA, correct?
I think there are cases where, even if the voltage applied to the device is the correct one (5V in this case) the drawn current is not equal to (5V)/(load impedance), because the source, although it can provide the 5V, may have a max output current of, say, 300 mA...