I just brought 12v battery from costco and theres no vent port. is that ok? or did they gived me the wrong ones?
Yep... VW has used low voltage batteries inside the cabin of vehicles for near a 100 years without issue. There's no proven incident of thermal runaway with a 12v inside a vehicle that led to fumes in the vehicle that killed anyone unless there was some other type of fire or collision damage. To further address your worries: 1) Amount of charge the Prius sends to the 12volt is so pathetically low it takes 12 hours of driving to recharge the 12volt whereas with all non-hybrid cars it takes less than an hour. 2) Because there's a robust battery venting system for the high voltage battery if it smokes, the 12volt, which sits next to the exterior vent of that system means there's already plenty of venting without the vent tube, 3) The Prius venting system for both batteries is so robust that starting in the early years of Gen3 Prius they eliminated that direct battery vent tubes from the hybrid battery pack and instead used the battery cooling system as the only needed venting.
What is the exact model of battery you bought? It is difficult to make a recommendation with no information.
