Identify this threaded and protected inlet, pls?

[JitneyBead]

I didn't do any of the major system replacements on the Beader's '64 Safari, so I feel like I didn't benefit from knowing whatever original systems were in place.

While dinking around making fixes to the plumbing after a week in the unusual sub-freezing Tuscon desert, I came across this thing in the back underneath the bathroom window.

It's obviously an inlet of some sort...the inside is threaded and it's connected to the plastic tube. It doesn't actually pass into the cabin, stays between the skins and drops into the utility opening at the back of the AS. The end of the tube has been cut - perhaps when systems were upgraded.

Do you know what it's for? I'm assuming water but it's such a small diameter opening, it's threaded and I have the "main" city water inlet on the back that is currently used.

Insights and education appreciated.

Jitney

[azflycaster]

It looks like the vent line for the battery.

[overlander63]

Back when your trailer was new, the battery had a cover that hose would fit onto. The cover would fit over the battery, and vent the explosive gases outside through that hole.

[JitneyBead]

Ahhh yes... I should have been thinking 1964, not 2011. Wet unsealed batteries.

My 12v system has been eliminated in favor of shore power only with a deep cycle used to power the freshwater pump, so I wasn't even thinking about batteries.

Doesn't explain why the inside of the outlet is threaded though. Maybe to connect a longer vent or for adding distilled water without opening the battery caps? Hmmm..

Thanks for answering though...