Hi Everyone!! I have a 2009 model toyota prius that my garage changed the 12v battery (not the HV) as it was dead. They replaced it with another battery that is completely different, but the car is running without issues so far. I noticed that there is a small pipe that connects to the previous battery (original), what is this small pipe for? is it ok to let it as is? Thanking you in advance!
This is the battery room ventilation hose (battery vent tube), shown in the catalog with part name code 28885A. The hose directs hydrogen gas, generated as the battery charges, outside the vehicle, reducing the risk of explosion or fire. See this previous discussion: Do we really need the12 V Battery vent? | PriusChat
welcome! some will tell you it's necessary, and others not. it's a safety decision you have to make based on whatever knowledge you can accumulate. i got a replacement battery that accepts the tube, and reconnected it.