Purchased this in preparation for a trip to Italy; I didn't want to risk blowing up my phone if a convertor didn't work properly! I tried this at home using Lithium batteries as someone else had suggested. My Galaxy S2 easily charged from 50% to full charge and there is still "juice" left in the batteries. This will be fabulous on the plane as well at the hotel. Would definitely recommend this to anyone travelling overseas or needing a back-up charger.