01-15-2013, 06:25 PM
That vibrate twice sounds like the sound it makes when you connect it to a charger and have it on vibrate mode.
As to why it is doing that on a repeating basis, I can only speculate. Perhaps it is loosing connectivity periodically or the circuitry in the docking device is periodically disconnecting it as its way to prevent overcharging. Or it is periodically disconnecting it because the iPhone is drawing more current than the device is comfortable with and a circuit is overheating and resetting on the dock.
As to why it is doing that on a repeating basis, I can only speculate. Perhaps it is loosing connectivity periodically or the circuitry in the docking device is periodically disconnecting it as its way to prevent overcharging. Or it is periodically disconnecting it because the iPhone is drawing more current than the device is comfortable with and a circuit is overheating and resetting on the dock.