Flashlight apparatus, battery cartridge for the flashlight apparatus, and methods of manufacturing the same. In one embodiment, a battery cartridge is disclosed that includes a cartridge housing having two battery-receiving cavities disposed therein and an end cap that interfaces with the cartridge housing. Each of the two battery-receiving cavities is configured to receive a series of cylindrical batteries therein, the series of cylindrical batteries being configured to power one or more light sources disposed within a flashlight apparatus. In other variants, methods of installing batteries within the aforementioned battery cartridge as well as flashlights that incorporate the aforementioned battery cartridge are also disclosed.