Timing for power-stealing circuits in smart-home devices

A smart-home device comprising:

• an energy-storage element that stores energy that is harvested from an environmental system;
• a power wire connector and a return wire connector;
• one or more switching elements configured to operate in:
• a first operating state in which the one or more switching elements create a connection between the power wire connector and the return wire connector;
• and
• a second operating state in which the one or more switching elements interrupt the connection between the power wire connector and the return wire connector;
• and
• a circuit that controls the one or more switching elements, wherein the circuit is configured to:
• detect a zero-crossing of a current received through the power wire connector;
• wait for a first time interval after the zero-crossing is detected;
• after an expiration of the first time interval, enable active power stealing for a second time interval by allowing the one or more switching elements to transition from operating in the first operating state to the second operating state during the second time interval;
• and
• after an expiration of the second time interval, disable active power stealing.