The present application relates to a battery-powered electronic device, such as an electronic hearing protector, with switchable electrical contacts. The device includes a housing enclosing the battery and an electronics assembly. The electronics assembly is powered by the battery, and the electronics assembly comprises a processor controlled by updatable software. The device further includes a first electrical contact that is a ground line; a second electrical contact that is a data programming line in a first state, and that is a charging voltage line in a second state; and a third electrical contact that is a clock line in a first state, and that is a charge enable line in the second state. The first, second and third electrical contacts are accessible from outside the housing. A switch enclosed by the housing changes the second electrical contact between the first state and the second state.