Porsche spec batteries have a vent tube so ventilation while attached to a battery maintainer is provided with the frunk closed.

 

Thanks to all who commented on this thread! And Macster, the car did act possessed with the battery about to fail!

As for the need for ventilation while charging the battery, I thought about this too, but I'm assuming that the vent tube off the battery would be sufficient if using the battery maintainer to at most trickle charge it.

Jim
2012 Boxster
Dk. Blue Metalic/Black

 

Jim, you are correct, our vent tubes do their job just fine. Only use a maintainer, not a trickle charger. Big difference.