A drying device includes a desiccant cartridge having a desiccant to reduce a moisture content of a gas located in an inner chamber of a housing. The drying device has a protective chamber which is configured to be introduced into the housing in a liquid-tight manner with respect to the inner chamber and which is connected to the internal space in a gas-conducting manner. The desiccant cartridge is arranged in the protective chamber. A battery system includes the drying device and a motor vehicle includes the battery system.