Stick up cam battery going dead after using solar panel

We bought the stickup cam battery and noticed that the battery would go dead after 5-6 hours. So we figured we would get buy the solar panel and connect to the camera since it's supposed to "charge the battery". Well now, about the same time every evening/night, we have to change the batteries out because they don't have a full charge and we want the camera to be in use for the middle of the night. Should we have just bought the stickup cam wired instead? To help with draining the battery, we changed the motion settings to the lowest possible and also people only mode (even though it still picks up the neighborhood cat). Any help would be appreciated.