An environmental monitoring device that includes a switching mechanism is described. During operation of the environmental monitoring device, the switching mechanism (such as a switch) selectively electrically couples a first electrical-connection node and a second electrical-connection node. For example, using the switching mechanism, an electronic device having a power source may be selectively electrically coupled to a second electronic device having a rechargeable battery. The selective electrical coupling may be based on one or more measurements of an environmental condition in an external environment that includes the environmental monitoring device by a sensor mechanism in the environmental monitoring device. This environmental condition may be associated with charging of the rechargeable battery. In addition, a control mechanism in the environmental monitoring device selects a charging mode of the rechargeable battery based on the one or more measurements of the environmental condition.