Accidental disconnection
 

I was cleaning the drain holes in front of the passenger side (NA-wise) and saw this disconnected piece ... I can't find where it goes. Does anyone know?

Thanks

It seems to be the venting tube for the battery fumes

Thanks Gilles! Now to locate a vent attachment on the battery ... it's an aftermarket the PO put in ....

If your battery is of the AGM variety, it will not have a connection for the vent line. Lead acid batteries will either have a tube, or a port for a tube connector.

I'm seeing a hole on either side but the porsche attachment won't fit. It also appears to be a BLEM replacement too .... does this look like an AGM? I'll have to leave the vent tube tucked away ...

FYI: BLEM indicicates a blemished battery. Usually a cosmetic defect or a battery that sat on the shelf for too long and was stripped of its decals and sold at a discount.

Are you sure that's a vent hole?
If so, you'll just need to make an adapter.

unfortunately I'm not sure ... there's a matching hole on the other side too ... as you eluded, there are no stickers etc. to aid identification.

I'm having the same problem with a recently purchased '04S. PO replaced battery and failed to swap out vent tube adapter leaving the battery unvented.

Check out this link:
https://www.amazon.com/BMW-Battery-Vent-Hose-Elbow/dp/B01L7U4MUU/ref=sr_1_fkmr2_1?ie=UTF8&qid=1503787574&sr=8-1-fkmr2&keywords=battery+vent+tube+elbow

The listing is for BMW's but I cross referenced battery requirements for the compatible BMW's in the ad and the 986. They were the same.
I'll be ordering a pair.

Don't know who told you this old wive's tale? (And you are aware that AGM batteries have lead-acid chemistry?)

Even if it's only for an exceptional circumstance, (e.g., battery or charging system malfunction), having a vent sure seems like a good idea to me when the battery is located in an area without plenty of natural ventilation, (and where sulphuric acid vapor-induced corrosion would be so damaging and expensive to repair) like is the case on our cars...

Nice find! That looks just like what I've got on my AGM battery...

http://986forum.com/forums/uploads02...1503791205.jpg

the holes on both sides are the vent hole. You're missing the 90 degree adapter. I'm sure pepboys etc sell the adapter. It's a small right angle adapter.
If would have it connected as there are quite a few reported exploded batteries, especially if you use a battery tender/charger

PO installed a Duralast Gold from Autozone which has vent ports on both sides of battery. Do I need to plug the unvented port or add another vent tube and "T" into the existing tube?

Crazy. I buy two AGM's each year for our waverunners...never have vent ports.

It would seem the determination of whether or not a battery has vent ports is application specific. I have SLA's in my Ram 1500 and Jeep Wrangler and they don't have vent ports.

I'm going to look around at the batteries next time I'm in Sams!