In a culture of shortcuts, there are a number of reasons why your car might have a missing battery vent elbow.

1. Urban legend has it that brand "X" batteries ship with a vent kit, but they are nowhere to be seen on the shelf. They get in the way somewhere enroute, so out they go in the garbage.

2. With or without a new vent kit, the installer decides to save a whole 30 seconds and tosses all vent hardware over the shoulder.

The remote vent serves two purposes. It provides a path for explosive hydrogen gases out of the enclosed battery mounting area. It also provides a path for acid fumes to escape the same area to prevent corrosion.

30 seconds saved by a "brilliant" shortcut can cost the vehicle owner many hours of remedial corrosion cleanup when it is finally discovered. Even after only 1 year, the off gassing can cause a nice line of rust along the seam running next to the battery in an otherwise pristine trunk compartment. The acid fumes are also not environmentally friendly to the trunk fusebox which is a few inches away.

Finding the right elbow can be an exercise in frustration involving untold hours of internet searches leading to spamvertising.

If you spend enough hours, you will finally stumble on:

BMW part# 61 21 1 377 835

A black plastic elbow that fits the battery and existing hose perfectly. A buck or two each.

The barbs are 0.2325" in diameter.

The battery will have two vents. One on each end. The one that is not used will need to be plugged. Most batteries ship with a vent plug molded to the plastic positive pole protector. It is 0.2390" in diameter. (batteries manufactured by Johnson Controls).

To avoid the consequences of a shortcut culture, the next time you have a battery installed, check the venting and raise cain if it is missing. Maybe after enough incidents at the service counter the installers will just give in and do it properly for everybody. The key to raising quality is to cause more pain to the purveyor than it is worth to use a shortcut.


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Thank you, Plums. You just saved me a lot of time and hassle. I bought my 2002 x-type a few months ago. I just had the battery go bad. As it turns out, the battery that was in it was the wrong size. I purchased a Maxx 94R from Walmart, and the instructions talked about venting. I located the vent tube under the battery case, but it had no elbow. I jury-rigged it with a smaller tube for now, but I wanted to get the right elbow. I found reference to the tube here: JaguarParts.com :: Original parts for your Jaguar but it doesn't say whether the tube comes with an elbow or if you need the "retainer" or "clip." I poked around the internet to see if I could get that BMW elbow you mentioned. Although the cost was $.50 to $.99, the shipping ranged from $7 to $15. Luckily, my local BMW dealer has the elbow you mentioned for $.79. Again, thanks for the tip.