Self-locking latch of an adapter apparatus

An adapter apparatus for connecting a rechargeable battery to a power tool, the adapter apparatus containing

• a latching device for latching the adapter apparatus to the power tool;
• and
• a locking device for locking the latching device,
• wherein the latching device can be reversibly adjusted from a first position to a second position, wherein, in the first position, the adapter apparatus is attached to a power tool and, in the second position, the adapter apparatus can be removed from the power tool, and in that the locking device can be reversibly adjusted from a first position to a second position, wherein, in the first position, the locking device locks the latching device in its first position and, in the second position, the locking device does not lock the latching device, and the latching device can be moved from the first position to the second position;
• wherein the locking device can be moved from the second position to the first position by connecting a rechargeable battery to the adapter apparatus;
• and,
• wherein the latching device has a height (H) and comprises at least one latching element, and the adapter apparatus further comprises a compression spring element having a spring force, wherein an interval (X) is established between the latching device and the locking device by the spring force of the compression spring element when there is no rechargeable battery connected to the adapter apparatus, wherein the interval (X) corresponds at least to the height (H) of the latching element.