Based on the technical data of the iPhone4, only home charger for 3GS will work car charger all actual model dont have enough power for give juice its same with the iPad this is pretty sure sorry for you of course case cannot too
Just that this charger is not certified for this model. Plus that it is not certified to work with the FM mode and that you may receive static. I just hit the ok tab below the warning and everything works okay including the FM and charging. I had this charger left over from when I was using it on my original iPhone.