At first glance one might think that simply plug in and it works well not really. I've struggled to find himself famous button found as a result of the 4 blue LEDs. Once the unit load and you connect your smartphone on, you must press this button to trigger famous charge if nothing happens ... first use and I have managed to load that has 3 telephones with a full load is barely 5000 mAh payload. I saw that the diodes lit when the magazine was in contact with the sun, but I have no idea the efficiency of solar charge. there is a kind of LED at the connectors but I have not seen a turn and I do not know what purpose it serves. to sum up, this represents at best a good 2 extra batteries ^^