Here's the thing I'm camping out in Indio, CA (middle of the desert, mid april with 113f-expected temperatures, full sun) for a music festival called coachella and I will not be able to charge my phone. I'm thinking of using a SOLIO Bolt or something of the sort to charge my precious 4S. Anyone have experience with solar chargers and camping? I plan on leaving the charger exposed all day to the sun in the car under the windshield and charging it from the battery pack at night. Will this work? I need my phone to last with use for 3 days!