[pjr710]

Ok i have to replace my battery. Just pulled the old one out, there’s a vent tube elbow in the battery but no hose. Great!

I will go buy a hose tomorrow. But when i do, what is the proper way to route the battery vent tube? Where should i place the end of the hose?

[gbalthrop]

Originally Posted by pjr710

Ok i have to replace my battery. Just pulled the old one out, there’s a vent tube elbow in the battery but no hose. Great!
I will go buy a hose tomorrow. But when i do, what is the proper way to route the battery vent tube? Where should i place the end of the hose?

The concept is to get flammable Hydrogen gas which can come from overcharge or overheat of battery Acid OUT of the trunk or Cargo area. On my E91 Wagon, the vent tube is on the Forward End of the battery, connected by a plastic elbow, and the tube runs DOWN from the elbow and out of the battery well.

Most Flooded Lead Acid (FLA) batteries that are sealed and vented have a hole in EITHER END, so you need to make sure your replacement battery has a PLUG inserted in the Rear end (Negative Post) or the vent tube is for nothing. Most "International" or Vented Batteries come with both the elbow and plug, and some come with a new vent tube.

ANYONE who can advise: Does the AGM battery have the same vent tube setup described above?

Does your car currently have an FLA or AGM Type battery? Do you know the size & Ah rating of the battery currently installed? Do you have INPA, ISTA, or other software or Scan Tool that can read current Setting/Option in the DME Power Management Module or CAS so you know whether or NOT you need to change the code/option?

If the battery currently installed is NOT the original battery, you should NOT assume that replacement battery is correct for your vehicle or that the Code/Option was changed for the correct TYPE & Capacity of the replacement battery. The battery compartment is large enough for an H8/Group 49 battery which should have at least 90 Ah capacity.

George

[pjr710]

George i just bought an interstate mtp 49/h8. I’ll have to code my car so i have that handled.

My problem is i just am taking this old battery out which was installed by a mechanic a few years ago and am realizing the vent tube hose is gone.

I need to know where it routes too. I don’t see a grommet for it to go to.

Is it supposed to dangle through the floor into the fender or something?

My battery has vent hole plugs in both sides. I believe on the e92 it’s normally plugged into the positive terminal side.

[gbalthrop]

Originally Posted by pjr710

... I need to know where it routes too. I don’t see a grommet for it to go to...

Your 20xx 335i E92 may be different from my 2007 328xi E91, but I'll show you mine even if you CAN'T show me yours.

Gray hose to Elbow & Grommet to left of two "Transfer Points" forward of battery.

George

[pjr710]

Originally Posted by gbalthrop

Your 20xx 335i E92 may be different from my 2007 328xi E91, but I'll show you mine even if you CAN'T show me yours.

Gray hose to Elbow & Grommet to left of two "Transfer Points" forward of battery.

George

You freakin rock man! I would have never found that. Mines likely the same. Thanks a million that made my night

[tx330i]

gbalthrop, thanks for the picture. My tube came off when removing the battery and I didn't notice the little elbow in the corner. To answer your earlier question, the AGM battery I just installed, Interstate MTX-48/H6 AGM does have a vent hole on both pos and neg ends of the battery. The vent tube plugged right into it on the positive side.

[gbalthrop]

Originally Posted by tx330i

... the AGM battery I just installed, Interstate MTX-48/H6 AGM does have a vent hole on both pos and neg ends of the battery. The vent tube plugged right into it on the positive side.

That's 50% of the solution.
The other half is: Do you have a PLUG in the hole on the opposite (Negative Terminal/Rear) end. IF NOT, any Hydrogen Gas or Battery acid that SHOULD go out the tube you installed on battery front is more likely to come out the rear opening.

I don't know that much about AGM batteries, but I would assume that if they have vent holes, they can eject Hydrogen gas or battery acid similar to their FLOODED counterparts. It's EASY to NOT THINK about plugging the vent on the other end, and the battery doesn't come from the store with any plug installed. "International" batteries with vent holes just come with an elbow and a small plastic plug, and YOU have to know what to do with them.
George

[tx330i]

Hi George,

I read about the plug in your post above. When I was at BMW parts counter today buying a new battery hold down bracket (something one of the shops along the way that replaced a previous battery apparently left off and discarded...), I asked about a plug for the vent hole. They didn't know about it. So for now, I don't have the hole on the negative side plugged. Where do I find a plug for it?

Edit: Actually, I just found an article on the web that said the battery should come with a plug, and showed a picture of it attached to the red positive post cover that gets removed. Sure enough, it has a plug on it that I almost threw away. Will put this on the battery tomorrow. Thanks!!!

Robert

[Bmwater]

Whats the purpose of the battery connection elbow? 61211377835

Is it a big deal if its not plugged in?

[gbalthrop]

Originally Posted by Bmwater

What's the purpose of the battery connection elbow? 61211377835
Is it a big deal if its not plugged in?

Read Post #2 in this thread. A young Brit may not know anything about either the Hindenburg or the Challenger disasters. BOTH were caused by combustion/ explosion of Hydrogen. So getting hydrogen gas from the battery OUT of the trunk or cargo area IS a big deal.
George