Hi. I am not electronically minded, but wouldn't the resistors used create heat. I found this diy charger above having too many wires and has a chance to possibly blow the iphone. I went to Jaycar and bought the 10AA battery holder and cigerette car adaptor and 12AA varta 2500 mAh batteries. soldered battery holder to adaptor, recharged batteries and plug in car iphone charger (already own one). It works. Not great to carry around. Just need to make a box to fit.