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Discussion Starter · #1 · (Edited)
Greetings,

I just inherited an '06 E350 Sedan and can see that I have a LOT to learn about it.
Today's issue is battery testing, replacement, and associated issues.

The red Visit Workshop - Battery Low indicator comes on when I start the car.
For about 5 minutes some convenience functions are disabled (such as the seat warmer).
After a few minutes, everything seems to be working. The car starts and runs fine.

I understand I have two batteries.
A main in the trunk, and an auxiliary under the hood. (I'm actually not sure which is which)
I also read (here) that they both need to be AGM batteries.
I have no idea what other specs to look for.
I also don't know what the proper associated procedures are.
I have a multimeter (and could probably learn how to use it)

TESTING
So, do I just access each battery and test each battery with the meter?
If one battery is good, let's say the main battery is good and the aux battery is weak, would a test still be valid, like are they connected? Would a good main battery throw off the reading for a weak aux batt.? Said differently, what is the proper testing protocol to test both, or each? (I actually suspect that it's the Aux batt, but I'm not sure.)

REPLACING
If it's the Aux batt, must I clip jumper cables (running from another car's 12V batt) to the battery clamps before removing the clamps from the terminals? There is a great deal of conflicting information and gadgets online. (I wonder if this car has jumper or charge posts and if so, where are they?)

I read this: "as long as you have your radio code - it's best to followup MB reset procedure for steering angle sensor + accessory systems (sunroof, each window) etc.. And then take 3 minutes and do a ECU/tranny reset - to reset system back to aggressive factory defaults." (I'm not sure if these comments refer to the main or aux.)

How do I find my radio code?
Where can I find DIY steps for the MB reset procedure and ECU/tranny reset? Is this a good thing to do?
I sure don't want to botch the electronics and don't mind going through a few steps specific to this car if that's advised. (Anything to avoid the dealership)

BATTERIES
I have not located a proper replacement for the main battery, and have no idea what to look for other than the AGM specification.

NAPA lists this one for the Aux batt.: NAPA AGM Automotive Auxiliary Battery BCI No. 400 200 A Glass Mat
Part # : BAT AUX14, Product Line : NAPA Batteries, Important Info : Auxiliary;AGM Valve-Regulated Battery Required, $107.99 /Each

HELP
What else should I be asking about?

TIA

DrCarl
 

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1999 S500; W140.051; 2003 E320; W211.065; 1973 220; W115.010
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It is possible that you may have a charging system problem.

You can look for date code on the Main Battery in the trunk to get an idea of whether it is >5yr old. Main battery is the 'Main Battery' and it's doing the work of starting the car and running 'conveniences', etc so it's the one you're concerned with.

You can display battery (system) voltage in instrument cluster by toggling thru the options and you can see the voltage before starting (I think) and can display it while running. That would be a way to confirm that the system IS charging. That doesn't necessarily mean that you don't have a charging problem though as when the alternator regulator brushes get worn down, the alternators work, but don't work as well. In general, after around 120~150k miles, an alternator or regulator replacement is to be expected.

Once you start getting those warnings in the instrument cluster, you're on borrowed time. Getting stuck is no fun and will cost you the price of the battery.

It's not unlikely that you may need to replace both the battery and the alternator.

Star system has a routine for testing the battery/charging system, but I've run it on a C230 (W207?) and seen it appear to pass marginally; the instr cluster warnings continued to pop up and the owner eventually got stuck and had to replace the alternator inside of 1 month after the Star testing routine.

The batt & alt longevity is best assessed firstly on how old they are then cross-correlate with other available data causing suspicion(s).
 

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Discussion Starter · #3 ·
It is possible that you may have a charging system problem.
Yup. Always a possibility.

You can look for date code on the Main Battery in the trunk to get an idea of whether it is >5yr old. Main battery is the 'Main Battery' and it's doing the work of starting the car and running 'conveniences', etc so it's the one you're concerned with.
I looked at the trunk battery and see no date.
I do see that it's a Mercedes battery a bar code that reads
A 005 541 10 01
12V 95 Ah 850 A

If the main battery is running the conveniences, I wonder what the auxiliary battery (under the cabin air filter, under the hood, passenger side) does?

You can display battery (system) voltage in the instrument cluster by toggling thru the options and you can see the voltage before starting (I think) and can display it while running.
Awesome!
This baby is in great shape for a 16 y.o. car.
Maybe it's the original battery?
Too bad the mileage is so low. It only has 30,000 mi.

Thank you.
 

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1999 S500; W140.051; 2003 E320; W211.065; 1973 220; W115.010
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I don't think that W211 system needs a radio code.

It's possible command unit w/ NAV might need it, but Audio 20 & Audio 50 non-NAV units don't use a radio code.

MB still offers the battery. It's superceded to 001-982-8208, but at $225 it's not very competitively priced. I replaced my W140 battery recently with an Autozone AGM battery that fit perfectly and was ~$135; 3yr free replacement, 5yr life. You can measure Ht/Wid/Depth on the battery and then cross check with Autozone type replacement. Also look for the 850CCA rating; sometimes there a multiple possibilities in the same form factor.

You can keep the electronics powered during a battery swap with a battery->OBD2 port device. You can find them cheaply on Ebay. Stll need to connect a battery w/ around 12V to the plug in device, but it doesn't require much power. I think there may be those saying they did it with a small 9V cell, but I haven't done that.

Those cars that had the radio code headunits had a little credit card sized card in with the owners manual stuff that listed the radio code. You could look in there, but my understanding is that the W211 doesn't require it.
 

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1922 Ford T no OBD, no ECU, no SCN
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No, you don't need AGM battery, but this is today's trend and finding equivalent of wet battery becomes difficult. That assuming that like most of us - you don't plan to drive your car on walls and ceilings, where AGM would make sense.
Testing battery is not that straight-forward and dual battery system not only brings more confusion, but system turns to be very sensitive and weakly torqued battery clam can trigger the error.
So start with displaying car voltage on cluster with engine off and then see how much voltage drop when you turn all headlights on?
Than start the engine and observe the voltage.
Finally get a scanner as you will need it for this car and hopefully the scanner will pinpoint the code.
The aux battery is emergency battery to supply enough voltage to SBC brakes to limp it to stop. It is not used in normal operations.
 

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Discussion Starter · #7 ·
I don't think that W211 system needs a radio code.

It's possible command unit w/ NAV might need it, but Audio 20 & Audio 50 non-NAV units don't use a radio code.
Although I've not learned how to use it, the car tells me what street I'm on and has functions like saving where home is. Isn't that what a Nav unit does?

MB still offers the battery. It's superceded to 001-982-8208, but at $225 it's not very competitively priced. I replaced my W140 battery recently with an Autozone AGM battery that fit perfectly and was ~$135; 3yr free replacement, 5yr life. You can measure Ht/Wid/Depth on the battery and then cross check with Autozone type replacement. Also look for the 850CCA rating; sometimes there a multiple possibilities in the same form factor.
Great info. Thanks.

You can keep the electronics powered during a battery swap with a battery->OBD2 port device. You can find them cheaply on Ebay. Stll need to connect a battery w/ around 12V to the plug in device, but it doesn't require much power. I think there may be those saying they did it with a small 9V cell, but I haven't done that.
I saw those with the 9V battery on Amazon. I'd not use something like that without verification that it's harmless and effective. Thanks!

Those cars that had the radio code headunits had a little credit card sized card in with the owners manual stuff that listed the radio code. You could look in there, but my understanding is that the W211 doesn't require it.
I don't have that card anywhere. I've seen reference to 'headunit' options (like reset?) on the main center display.

I do have a weird little solid metal "thingy" that has a small screw at one end and is about the size of a key fob. No clue what it is.

Thanks for the great info.
 

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Discussion Starter · #8 ·
No, you don't need AGM battery, but this is today's trend and finding equivalent of wet battery becomes difficult. That assuming that like most of us - you don't plan to drive your car on walls and ceilings, where AGM would make sense.
You may assume that I'm not planning on wall or ceiling driving...lol

Testing battery is not that straight-forward and dual battery system not only brings more confusion, but system turns to be very sensitive and weakly torqued battery clam can trigger the error.
Interesting about the torque.

So start with displaying car voltage on cluster with engine off and then see how much voltage drop when you turn all headlights on?
Than start the engine and observe the voltage.
Finally get a scanner as you will need it for this car and hopefully the scanner will pinpoint the code.
The aux battery is emergency battery to supply enough voltage to SBC brakes to limp it to stop. It is not used in normal operations.
Great info. Thanks!
 

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1922 Ford T no OBD, no ECU, no SCN
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I would not believe in battery clamp starting the engine and then triggering the error if that would not happen to me.
I went on 1-week vacations and Murphy law promptly triggered the error on day 1.
I drove with ScanGauge, so I could see proper voltage, yet the convenience shut downs kept on coming on and off whole vacations.
Only better inspection at home found the culprit.
 

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2008 E350 4Matic, 2011 E350 4matic
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You switch to the temperature display with the car not running but the ignition on and hit the reset button 3 times and it will display the voltage. Then you can start the car and see what the voltage is. The charging for an AGM battery is different than a regular lead acid battery but a regular one will work fine. I would suggest the Champion from Pepboys.com. It's an H8 battery. It's a JCI battery, same as the Varta battery that MB used. The date code on the Varta battery is on the terminal. It's stamped with a week and year code. You should search around and be aware that the 2006 had the balance shaft issue, however with such low mileage, it might be a while before you encounter it. There are many issues on youtube on how to check for it.

You don't really need that 9v memory saver. You also have to use it right. The cig ligther is off when the key is off so you need to make sure the key is turned on when you have it plugged in when changing the battery. But I've had the battery changed and dead without them, it doesn't really lose much info when the battery is dead. Usually just to normalize it is to open the sunroof and windows and hold the buttons for an extra 5 seconds when they're both open/closed will do it. You can also take the car to any auto parts store and they will load test the battery for free to tell you if it's any good or not. Could just need to be charged if it hasn't been used very often. Most of them don't install for free anymore, they don't want to screw up a Mercedes. Basics of installing the battery is really the weight, it's a heavy battery. But always disconnect the negative first, then the positive and connect positive first, then negative. As mentioned earlier, a loose connection will also give you battery errors so make sure it's tight enough. And be careful with the postive/negative terminals, too many old stories on here of people mixing it up and it's a really basic, stupid mistake to make, fries out a few things when you mix them up.
 
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