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'14 E350, '07 CLK350, '01 SLK320
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Discussion Starter · #1 ·
This morning I replaced the 6 year old NAPA battery in my S320 with a genuine M-B unit. The swap itself was pretty easy, but I realized I was missing a key detail, which how is the battery vent is configured / connected. The battery I pulled out just had the little 90 degree elbow on it pointing down. My S420, which has an Interstate battery, has no vent tubes connected at all.

Would someone who has the M-B battery in their car please post a picture or description of their vent set-up so I can make sure I get it right? Thanks!
 

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97 S500coupe. 97 sl320 2000 Corvette 1999 V star 650 Classic
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Batterey ventilation

This morning I replaced the 6 year old NAPA battery in my S320 with a genuine M-B unit. The swap itself was pretty easy, but I realized I was missing a key detail, which how is the battery vent is configured / connected. The battery I pulled out just had the little 90 degree elbow on it pointing down. My S420, which has an Interstate battery, has no vent tubes connected at all.

Would someone who has the M-B battery in their car please post a picture or description of their vent set-up so I can make sure I get it right? Thanks!
This is an interesting subject. I recently replaced the batterey in my 97 SL320. The service records showed the batterey in my car was almost 8 years old and was the second batterey. Although it still seemed to function just fine I got a crazy idea to go ahead and fix something before it became a problem. I purchased a new batterey from the dealer (this is a wole other story but I'll save it for another day). When I got ready to make the switch I found that when the previous batterey had been installed the mechanic got lazy and did not bother to connect the vent. Interesting since the receipts tell me the batterey was purchased and installed by a MB dealer in the Sacramento CA Area. After I saw this I checked my 97 CL500 and low and behold - no vent connection either. In this case the records indicate the batterey was installed 2 yrs ago by an independent. I suspect that the majority of replacement batteries get installed in Mercedes (trunks) without the vent being connected.
Jan
 

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Different chassis but similar setup in the W210, the OE battery has the little connector on the end of the battery to the vent tube (which goes under the floorpan as the battery is under the rear seat). My replacement Interstate battery came with a "vent tube kit" as the vent is in the middle of the battery, with a flex tip that went over the nipple on the battery, then right-angled to run over to the side, with an adapter to connect it to the clear vent tubing.

Any conventional battery inside the passenger or trunk compartment needs to be vented. Aside from being explosive, the vapor is also corrosive and in sufficient concentration, deadly.

The newer gel-mat type batteries do not need to be vented in any configuration.

Good luck.
 

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'14 E350, '07 CLK350, '01 SLK320
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Discussion Starter · #6 ·
@Check Codes (LOVE that handle, BTW): That was my thought exactly. I couldn't find any documentation about it on AllDataDIY or WIS, so that's why I started this thread. I can't believe that a battery situated where it is would not be vented.

While the battery was out, I poked around the area with a flashlight and couldn't find any trace of vent tubing or any kind of pass-through. I queried my parts person over at the dealer and the only thing she could find was a listing for a 90 degree elbow. Nothing else....
 

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97 S500coupe. 97 sl320 2000 Corvette 1999 V star 650 Classic
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Plastic elbow

@Check Codes (LOVE that handle, BTW): That was my thought exactly. I couldn't find any documentation about it on AllDataDIY or WIS, so that's why I started this thread. I can't believe that a battery situated where it is would not be vented.

While the battery was out, I poked around the area with a flashlight and couldn't find any trace of vent tubing or any kind of pass-through. I queried my parts person over at the dealer and the only thing she could find was a listing for a 90 degree elbow. Nothing else....
This is exactly what I ran into when I replaced the batterey in my R129 last month. When I picked up the new oem batterey at the dealer I asked the parts mgr about ventilation. He said I would need the elbow - this is sold separately. When I took out the current batterey I discovered it had been installed by a Mercedes dealer almost 8 years ago without a vent. At each end of the oem batterey is a small round vent hole. Apparently what you are supposed to do is plug one end and use the 90 degree elbow to connect a vent tube to the end closest to the front of the car. I have no idea how you are supposed to plug the vent at the back of the batterey. In my case I ended up just installing the batterey without using the elbow. I figure that if it worked for the past 8 years it can't be a big deal. Then I checked my 97 C140 - same deal not vent, elbow or anything used to plug the other end.
Jan
 

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Discussion Starter · #8 ·
Interesting. My new battery came with a vent plug attached to the positive terminal cover. The installation instructions went something like this (paraphrased):

1. Install positive cable

2. Install negative cable

3. If installing vent, plug vent tube into one of the vent holes, plug the other one with the plug attached to the terminal cover.

4. If not installing the vent, you don't need to do anything.

Strange... :confused:
 

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97 S500coupe. 97 sl320 2000 Corvette 1999 V star 650 Classic
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Venting the batterey

Interesting. My new battery came with a vent plug attached to the positive terminal cover. The installation instructions went something like this (paraphrased):

1. Install positive cable

2. Install negative cable

3. If installing vent, plug vent tube into one of the vent holes, plug the other one with the plug attached to the terminal cover.

4. If not installing the vent, you don't need to do anything.

Strange... :confused:
Where did you get your batterey? I got mine from the Mercedes dealer in Monterey CA. Part #0000-982-33-08. When I asked to verify it was set up to vent I was told I needles the "vent tube". What they gave me was part #0000-990-38-92. This is a small 90 degree white plastic elbow. Apparently it is designed to stick in one end of the batterey and you would supposedly reconnect the previously connected vent tube which I assume runs down and out under the car into the wheel well. This does not give you anything to plug the other vent hole at the opposite end of the batterey. I got absolutely no instructions on all this with my oem batterey. Ended up installing it just like the one I removed - no plug and no vent tube connected. I suspect the whole issue of venting these batteries is a safety/liability issue and they were vented to protect Mercedes from potential lawsuit as the manufacturer. The other issue involves the potential from the gases being released from the unvented battery causing a caustic reaction to the metal tray the battery sits upon in the trunk. I suspect that if you were able to do a "scientific study" on the % of replacement batteries in the trunk of R129 and W140 cars you would find the vast majority are not vented.
Jan
Jan
Jan
 

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Discussion Starter · #10 ·
I suspect that if you were able to do a "scientific study" on the % of replacement batteries in the trunk of R129 and W140 cars you would find the vast majority are not vented.

Maybe I should turn this thread into a survey. :)
 

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97 S500coupe. 97 sl320 2000 Corvette 1999 V star 650 Classic
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DIY opportunity

Maybe I should turn this thread into a survey. :)
Perhaps someone who can speak to the reason why the batteries need to be vented could post a tutorial to show others how and why this is to be done. The ther option would be for someone who knows to let us know that they don't really need the vent. Personally I expect there is a good reason why these were vented when built.
Jan
 

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3phase-4pole
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Apparently I dont have my vent as well. Here are some pics from the R129 section - click

Since I have my battery connected to a trickle charger, a vent would be key. I will get this done when I get the chance
 

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1997 S500V, 1999 S500 grand edition, 2006 s65 amg
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new Original battery did not have a drain tube at all. I bought mine December 2013. I might be wrong but I couldn't find any outlets but it was on the pricey side (had an interstate that lasted 8 years according to records)
 

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1994 S420
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I just reolaced my MB battery. OEM is not vented. No vent line for battery anywhere. I replaced with an AGM battery. Got it at Advanced Auto. List was $182 and I found a $50 coupon online for a $132 net cost. They loaned me tools, rag and cleaner to install in parking lot which worked out great.

Battery

Autocraft Gold Absorbent Glass Mat (AGM) batteries are for today's power hungry vehicles. Autocraft Gold AGM batteries are engineered to provide up to 2x the life of a standard flooded battery. They are ideal for vehicles with electrical accessories (DVD players, heated seats, GPS, plug-in accessories) which put a demand on the battery.

Product Features:
Up to 2x the life of a standard flooded battery
Engineered with PowerFrame(R) positive and negative grids, delivering longer battery life
Provides extended life in high temperature climates
Excellent starting power even in low temperatures
Spill-proof design is great for mounting in vehicle cabins and trunks
3 year free replacement warranty

Product Application(s):
1994 Mercedes-Benz S420
OE Group H8 AGM
OE CCA 825

Acid Included: Yes
Battery Type: AGM
Battery Usage: Auto/Truck
BCI Group Size: H8
Cold Cranking Amps: 900
Cranking Amps: 1000
Deep Cycle/Starting: Dual Purpose
Height: 7.5
Length: 13.94
Maintenance Free: Yes
Reserve Capacity: 160
Terminal Type: SAE
Weight: 59.45
Width: 6.938
 

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