bigswol2

Has anyone else encountered this message. This will shut down all the convenience features. I have added two amplifiers to my car. Is there any way to avoid getting this message short of removing my stereo?

paulv

A guy I work with had this big amp installed in his car (non-MB) and the installer powered the amp directly from the battery. This approach is a big no-no with an MB. How are your two amps wired?

Regards,
paul...

bigswol2

Directly from the battery in the truck I think. How should they be wired?

AndrewAZ

Get another battery...


BTW how powerful are these amps?

okc329

some of the newer Mercedes cars have two batteries. One is considerably beefier than the other. Maybe your amps are wired up to the wrong one. On the otherhand, maybe the amps are just too much for the cars electrical supply.

bigswol2

one is a memphis 1000 which is a 300 watt 4 ohm mono amp and the other is a PPI 4800 that is a 80 x 4 in 4 ohms

AndrewAZ

The E class has 2 batts, One of a normal one that is in the trunk that mainly powers accessories, the one under the hood is a motorcycle type batt used to start the car. T

sinocomp

Hi , could you kindly tell me where to find both batteries ? I open the hood and trunk, can't find it . I have 03 e500 , tks.

p

bigswol2

the big battery is in the trunk is beside the spare.

Barry45RPM

In the trunk, under the carpet where you'd expect the spare to be there is a bowl shaped compartment. You have to remove that big plastic shelf which contains the bowl shaped compartment & look under it where the spare & Jack are stored. The battery is next to the spare, long & skinny.

The underhood battery is (as you face the opened hood with your knees touching the bumper) on your left side all the way in the back near the firewall. It is covered with a black blastic box. It is small & cube like in size.

paulv

bigswol2,

The battery in the trunk is the one that starts the cars and runs everything else. The small battery in the engine compartment is a standby battery to keep the SBC electromechanical braking system powered in the event the main battery's voltage drops below a certain level.

You need to know what the current draw is for both amps (output wattage into speakers doesn't help), and then find a vacant position in the fusebox that has a rating higher than your amps total input current. Then you can use that to power your system.

The bottomline is that there's a battery control unit (BCU) that controls the draining and charging of both batteries and you cannot bypass this.

I suggest you post on the audio forum for help to see what otehr people have done (successfully).

Regards,
paul...

bigswol2

Thanks a lot Paul.

mbnj

Just got the same message on the '05 sedan this AM- "Shutting down convenience functions". It then went to All RED and said to pull car off the road. I called Roadside Assistance, they swapped out a brand new battery even though the car only has 13K miles on the original. Same messages came back up immediately, Mercedes had car towed in to service a few minutes ago. RA mentioned there was an "open ticket" on the alternator or regulator and that it normally was addressed when brought in for the SBC Brake recall. We did the brake recall a few weeks ago but had no mention any regulator or alternator work? High marks to Roadside Assistance. People on phones were very responsive despite early hour, got call backs in less than three minutes from local service and to my house in less than an hour, no issues swapping out for new battery when he saw how low the original battery was and then called tow and service for pickup once he saw no improvement- service tow got here within 30-40 minutes. Nice job and appreciated.

sosh

Wrong!! The small battery under the hood is for electronics and the large battery in the trunk is for starting and heavy draw accessories.

W211 Ryda

Okay...same thing happened to me over the weekend while I was driving. I just took a pic of my dashboard since I couldn't write down the malfunction message. The only electrical modifications done to my car is my HID kit for my fog lights, which was off at the time and my lowering module. The battery has been replaced about a year ago because the original one was defective. I've had all the recalls done to my car. After 30 mins of driving, the malfunction warning went away. Hopefully Konig could chime in on this.

x-tian-230k

Funny,

Mine did the same thing while driving on the highway. I dont have an electrical mods done to my car except for lowering it via star diag done by the dealership. This is not becoming a coincidence....

starbrite

Barry mentioned the trunk one. The second small battery is under this cover , on the passenger side of the engine compartment, close to the firewall. Press the release tab on the catch circled in red. (ignore blue circle, it's from an old post). The cover is hinged and will swing up.

Edit: Note that this is f/an '04 E320, see paulv post below....your's may be there.

paulv

Hey Starbrite,

You have to do all that on your 04 E320? On my 03 E320, I just remove the screw on the front of the combo filter cover (on the wheel well) and pull up on the cover as it's hinged -- I've already replaced my combo filters a couple of times and also replaced the aux battery ($125 at the MB parts counter).

Regards,
paul...

starbrite

hmm...IIRC, you're partly correct. You do have to remove this cover on the '04, however not the 2 nuts (which hold the frame), just the catch. That pic was from an old post where I was asking which to remove. I'll edit the post above.

paulv

OK, good! I was thinking that you were stuck doing more work to replace those carbon/charcoal combo filters (that only seem to filter out dust, a paper filter would have sufficed), whereas my 03 was an easy changeout.

Regards,
paul...

Clinton Horn

My 2003 E-320 posted the same code several times. I had it inspected under warranty and they discovered a loose battery cable. I think it was concealed in the trunk as I had checked the connections at the battery. This is probably a long shot. I believe that I read in the repair ticket that the alternator was not able to deliver the amperage required and the system detected it as an electrical shortfall. It is a staged reduction to preserve the driveability of the car. Mine had the alternator / voltage regulator recall done. I read somewhere that the small battery was dedicated to the electric brake servo.

bigswol2

I've been advised by my stereo installer I may need a second battery... what are you guy's thoughts on this.

paulv

I don't know how you're going to incorporate another battery into the circuitry for the reasons I stated previously -- the battery control unit.

Go to http://www.mercedestechstore.com and look at the training files. Under the W211 stuff, there's a pdf file about the dual battery setup. This will provide you info so that you can either forget the whole idea or find some way of hooking up your amps. The file is too big to post here. You should really solicit advice from the Audio section on this forum -- maybe someone has [successfully] done this before.

Keep in mind that the electronics in these cars are very expensive.

Regards,
paul...

starbrite

Yesterday, while rolling the car out of the garage (ignition on. in neutral) I got the same message.
Turned off the ignition and measured the battery CCV (closed circuit voltage) and read 11.93 volts,
which indicates the battery was 75% discharged. As soon as I started it, the message went away.
It had been about 10 days since I last drove it, but that still seemed a bit extreme to me.

Edit: BTW, if any of you aren't aware of the reference voltages for a battery's charge state, here they are :

12.00 volts 25% charged
12.35 volts 50% charged
12.50 volts 75% charged
12.75 volts 100% charged

Note that these are Open Circuit Voltages, that is battery ground disconnected.
CCV's (cables connected) will be slightly lower but are still a valid reference for a battery's charge state.