Unfortunately I had to give back the battery case again :-( When commissioning initially saw everything quite well from that case invited the internal battery and gave his charge too quickly ans iPhone from. Unfortunately, it worked only when the case was connected to a USB charger. Since the case is also explicitly advertised so that you can synchronize via the supplied USB cable and load on the computer, I also took advantage of this feature. Still, that did not succeed! Neither the iMac, the MacBook Pro, on the PC, service PC ... Insufficient power supply connections not all, the OS can not push it, try another USB cable - nil ... So who actually before, the iPhone when loading on the computer and to synchronize the Case allow, should expect that the iPhone is not recognized and neither invites nor synchronized. :-(