Does anyone know of any consequences of NOT have a vent hose hooked up on a new battery? Ive never come across this before in any of my other cars and figure maybe in the Cabrio its just a hangover from the hard top cars having the battery back in the trunk so needing to vent any gasses generated to outside the cabin space?

I had to replace a battery at the weekend, and it was only when I took the old one out that I found the vent pipe attached. The replacement battery I got is cross referenced to 1st Gen Mini Coopers, so on paper at least is "the correct replacement" but it does not appear to even have a vent. There is a dummy point on the case molding where the vent on the old one was, but its basically blanked out. If it was a hard top car I'd be more concerned. Am I wrong?

 

The battery gives off hydrogen as it’s charging. Since our Mini batteries are more or less sealed up inside the battery box, hydrogen could build up inside the box if it weren’t deliberately vented.

At this point you might be able to return the battery they gave you, but they may not have a replacement with the vent.

 

Theres no lid on my battery box, maybe there was once but I didnt even realise there was supposed to be one, its just sitting out there venting to whatever air is under the hood. Thats probably why it seemed odd that is was vented.

 

Mini Cooper S has the battery in the trunk under the carpet....all other cars have battery under the hood....I would think you would not need a vent hose from the battery if it's in the engine compartment.

If your car is the "S" version, then the battery needs a vent out from under the rear carpet in the trunk. You don't want to be breathing sulfuric acid vapors

Bryan

 

As posted above, venting a battery in the engine compartment isn’t as critical like one in the passenger compartment, but I would run it as designed if possible.

The batteries I’ve seen lately had ports on both sides with plugs in them so you can hook up the vent only on the side that’s needed. The plugs are tight fitting and look permanently sealed, but usually just pull out. This might be the case with the dummy port you’ve described.

 

Mines a "Justa". Thats kinda what I was thinking. If I expire from breathing in battery gasses Ill be sure to have my widow come back here and let you know:D

 

If your battery box lid is gone I wouldn’t worry about it.

My 2004 R50 has the vent present, and I can see how hydrogen might build up in there with the lid clamped down.

Maybe not all Mini’s had covered battery boxes, I don’t know.