A power transmitter for wireless power transfer includes a sensing system, a feedback mechanism and a control and communications unit includes a controller configured to receive object detection data from the sensing system, if a power receiver is detected, reset an alert timer, if the power receiver has been detected and a disconnect is detected, determine if an alert timer value is greater than an alert threshold, if a disconnect is detected and the alert timer value is greater than the alert threshold, instruct the feedback mechanism to output an alert. The power transmitter further includes an inverter circuit configured to receive a direct current (DC) power and convert the input power to a power signal and a coil configured to transmit the power signal to a power receiver, the coil formed of wound Litz wire and including at least one layer, the coil defining, at least, a top face.