MBNUT1

Took it in to the dealer today because I was getting a low battery convenience features disabled message. The seat heaters wouldn't turn on when I first started the car. They replaced the main battery under warranty. When I dropped the car off it was a mess covered with salt because it has been to cold to wash it. When I picked up I was honestly startled by how new and beautiful it looked. It was like "Thats my car?" I hurried up and hopped in it before somebody decided that they had made a mistake. Cleaned up black on black W211's with 17 in appearance package wheels are freaking gorgeous

E200turbo

What if you just drove off, acted dumb until the dealer or police called you? I'm not saying to steal the car, just take a normal, sedate test drive.

mcleantmw

Lately I'm getting an occasional Battery alert message and that the accessories have been disabled.......does that mean the battery is going bad? We've had fairly cold weather here in the Washington D. C. area lately which I know strains any battery.

vettdvr

YES It is only a matter of time before it fails. A simple voltage test at the battery terminals with the engine running to show voltage about 13.2 will indicate alternator is charging. Then if you have low voltage warning the battery is failing. I would just replace it now to avoid a problem.

MBNUT1

That was the dealers position. They were kind enough to want to replace while the car was still under warranty. How much is a new battery for it like $250??

Scambo

Also check battery control module. Very critical to ensure this is operational.

Polar Bear

Roadside Assistance will install the battery for around $130 and free labor.

vettdvr

The battery control module could be at fault,, but I have seen more battery failures than modules.

I thought I had a battery going out also when I got the malfunction warning. So I went shopping for both aux and main bat. I found a aux battery at Autozone for about $70 and they also had the main battery for about $149. This was a conventional acid type battery. Autozone could order a AGM battery for the MB at about $189. So there are "other" places than the dealer that can get you a battery. Just make sure that the battery is CORRECT for the MB and has the vapor VENT line to prevent acid vapors from building in the trunk. The replacement batteries will have a plug in the top that will allow you to connect the car vent line.

You don't have to buy the main battery at the dealer. You probably will have to reset the memory items in the car if you change it. Instructions are in the owers manual.

Long Islander

Are AGM (stands for "absorbent glass mat" for those who are curious) completely sealed like Optima batteries -- with no need for the vent tube?

vettdvr

There may or not be a vent tube. AGM is absorbent glass mat but there still might be vapors that would vent. The acid is in contained in the glass mat. The real advantage is no leakage around battery post or case seals as in a side or top terminal battery. I have had a top terminal break the seals and acid wick out die to vibrations. The AGM is suppose to prevent this. You have your choice conventional battery or AGM.

igolfchip

I'm having same issues with my battery. A couple questions:

1) What's a good / great battery for replacement? A local repair shop spoke highly about the Interstate vs. MB OEM battery.

2) Where can I save money on this? Can I just order at local autozone and save both on cost and installation?

Thanks in advance!
Chip

vettdvr

My local AZ only sold the top of the line battery for the MB. It met the specs and had 3 yr replacement warranty. If I remember it was $139 and it had all the necessary vents. The bat had small plugs that you removed to install the car vent line.

Interstate is also a good battery. I think both would work well. However to get an AGM would cost about $50 more if you want to go that way. vettdvr

Long Islander

You might want to look into the Deka 9AGM49, an AGM battery, which is available in my area for $150. The specs are quite impressive (900 CCA, 185 minutes reserve capacity). Go to www.dekabatteries.com

wdlanning

I received the red battery trouble alarm in my 320CDI. Upon inspection, one of the terminals had broken off due to corrison. For the past week, it must have been making contact off and on.

I just replaced the battery without disconnecting the main battery since it was already out of the circuit. I did not receive any problem alerts after the replacement.

Based on the discussions herein, I was wondering why the MB process called for disconnecting the main battery. I am guessing that it may has something to do with the battery relay. But I really don't understand the reasons for it. Also, was I just lucky that no damage was experienced? I checked the charging voltage at both batteries and they were OK.

I would appreciate some feedback.

vettdvr

They want you to disconnect the main battery so that if you accidently touch the + cable from the aux battery to ground you won't burn out the car wiring. I did not disconnect the main battery either, but I held the + from the aux in my hand until it was reconnected to the new aux battery.

You did a good job in the repair but I don't know how you repaired the lug on the wiring harness at the broken lug.

Clinton Horn

Just finished replacing the aux battery (stamped 46 / 02) so I think we got the best out of it. I went to Batteries Plus (maybe a local chain?) and purchased the referenced size in AGM 12 ah ($70). The guy said they just installed one in anther E and assured me it would fit. The error message kept saying it was disabling the audio. I guess that is about as harmless a warning as you can get. Used vettdvr's instructions and everything went fine. ESP was disabled but lock to lock on the wheel fixed that. Reset the sunroof program and clock. Off to the races. I think this will be a common problem as the cars start approaching 48-60 months in service.

vettdvr

Well done glad it worked for you. I learned the hard way after buying the MB battery and installing it. By using the old battery in hand I was able to match up to the Autozone replacement.