Charging devices and methods for charging electrically powered vehicles are disclosed. One example charging device includes a processor configured to at least partially control a state voltage and a detection circuit coupled to the processor. The detection circuit includes an energy storage device and a discharge circuit coupled to the energy storage device. The energy storage device is configured to be charged by the state voltage. The discharge circuit is configured to discharge said energy storage device in response to a discharge command from said processor. The processor is configured to determine a charging state associated with the electrically powered vehicle based on a voltage across said energy storage device.