I often go Gold & Gemstone hunting and use quite a bit of 12volt equipment, including a forgotten 12v cooler plugged into the dash. Upon leaving the car for a day to prospect a small stream, the cooler drained our battery dead. We returned with only about 2 hours of daylight left, found the battery dead and I immediately removed the charger from my backpack and began charging the battery with direct sunlight. As the sun was setting we "tried it" and there was just enough charge to start us up and we drove the 12 miles out of the forest instead of having to walk it out for help.Not only does the product work, but it has changed the way I think about solar energy. Needless to say, since it saved us that day in the forest, I am rating this product with 5 stars.