Abstract: A key storage device (1) has a tubular housing (8) having an open proximal end (14) and a distal end (15), and a sliding carriage (2) which is insertable into the proximal end (14) of the housing (8). The sliding carriage (2) has a compartment (4) for a key to be stored, and is displaceable between an open position in which a majority of the sliding carriage (2) is outside of the housing (8) and the compartment (4) is accessible for key retrieval, and a closed position in which the majority of the sliding carriage (2) is inside the housing (8) and the compartment (4) is inaccessible. A lock mechanism (12) is arranged within the tubular housing (8). It has a locked state in which the sliding carriage (2) is kept locked in its closed position and prevented from being displaced to its open position, and an unlocked state in which the sliding carriage (2) may be displaced to its open position.

Abstract: It is provided a protection circuit for protecting a battery comprising a plurality of lithium primary cells. The protection circuit comprises: a switch configured to control when the battery supplies power to a load; and a control circuit being configured to: detect, at a first point in time, when a voltage across at least part of the battery falls below a threshold voltage; and open the switch when the voltage across at least part of the battery is remains below the threshold voltage during a preconfigured duration from the first point in time, wherein the opening of the switch is irreversible.

Abstract: A key storage device (1) has a tubular housing (8) having an open proximal end (14) and a distal end (15), and a sliding carriage (2) which is insertable into the proximal end (14) of the housing (8). The sliding carriage (2) has a compartment (4) for a key to be stored, and is displaceable between an open position in which a majority of the sliding carriage (2) is outside of the housing (8) and the compartment (4) is accessible for key retrieval, and a closed position in which the majority of the sliding carriage (2) is inside the housing (8) and the compartment (4) is inaccessible. A lock mechanism (12) is arranged within the tubular housing (8). It has a locked state in which the sliding carriage (2) is kept locked in its closed position and prevented from being displaced to its open position, and an unlocked state in which the sliding carriage (2) may be displaced to its open position.