A battery vent cap capable of push-in installation and turn-out removal. The cap includes bayonet tabs. The tabs in turn each include a ramp portion to facilitate movement of the cap bayonet tabs past bayonet tabs in a battery vent port as the vent cap is inserted into the port axially without substantial rotation. The interfitting bayonet tabs retain the vent cap within the vent port and also permit the vent cap to be unscrewed and removed from the vent port. In a preferred embodiment, the vent cap includes a swivel connector to which a watering hose may be connected. The swivel enables the vent cap to be unscrewed from the vent portion without having to remove the watering hose from the swivel connector.