Batter not charging Alternator fine
Thread Starter
Newbie
Joined: Apr 2016
Posts: 2
Likes: 0
2010 E350 4matic
Batter not charging Alternator fine
Is there a fuse of some sort between the alternator and the battery.
Had a siren inside the car not outside go off for about 6 minutes before it quit. A burnt smell from the 2 vents under command and now battery does not charge
Had a siren inside the car not outside go off for about 6 minutes before it quit. A burnt smell from the 2 vents under command and now battery does not charge
MBWorld Fanatic!
Joined: Mar 2014
Posts: 3,107
Likes: 394
From: West Central Florida
2011 E550 P2 4M Sedan
Not aware if there is a fuse or not, but have you had the battery tested? If the engine can run after jumpstart, I would look at the battery as the electrical connections are fine and the alternator can power the systems.
In regards to the smell, if your battery is under the hood near the air intake (like my 2011) then I could see a smell issue if the battery got overheated. But if you battery is in the trunk like early/mid 2010's, then I don't see the connection to the smell.
In regards to the smell, if your battery is under the hood near the air intake (like my 2011) then I could see a smell issue if the battery got overheated. But if you battery is in the trunk like early/mid 2010's, then I don't see the connection to the smell.
Thread Starter
Newbie
Joined: Apr 2016
Posts: 2
Likes: 0
2010 E350 4matic
The battery is fine. Tested and charges fine. No alternator output back to terminals but is is not the alternator. Whatever caused the screatching alarm inside the car (it was not the car alarm that is outside of the car) burnt something out. There is something between alternator output and battery input that was affected.
I have heard that there is a sealed 150 amp fuse between them but cannot fine a diagram of the battery charging system for this car
I have heard that there is a sealed 150 amp fuse between them but cannot fine a diagram of the battery charging system for this car
MBWorld Fanatic!
Joined: Mar 2014
Posts: 3,107
Likes: 394
From: West Central Florida
2011 E550 P2 4M Sedan
Perhaps the location of this secondary alarm is related to the battery issue. Haven't heard (no pun intended) of any other audible alarm in car. Any aftermarket items installed off main battery?
When you say no alternator output back to the terminals at the battery, what do you mean? Alternator output on the W212 is notoriously low for battery recharging and often only shows 12.5-6 volts at the battery when the car is running.
When you say no alternator output back to the terminals at the battery, what do you mean? Alternator output on the W212 is notoriously low for battery recharging and often only shows 12.5-6 volts at the battery when the car is running.
Newbie
Joined: Aug 2019
Posts: 3
Likes: 0
2010 W212
Perhaps the location of this secondary alarm is related to the battery issue. Haven't heard (no pun intended) of any other audible alarm in car. Any aftermarket items installed off main battery?
When you say no alternator output back to the terminals at the battery, what do you mean? Alternator output on the W212 is notoriously low for battery recharging and often only shows 12.5-6 volts at the battery when the car is running.
When you say no alternator output back to the terminals at the battery, what do you mean? Alternator output on the W212 is notoriously low for battery recharging and often only shows 12.5-6 volts at the battery when the car is running.
MBWorld Fanatic!
Joined: Jan 2009
Posts: 9,224
Likes: 1,798
From: V E G A S
1922 Ford Model T / no OBD
There are 2 kinds of charging systems on W212
-standart where alternator pumps constant voltage
-regenerative charging, aka blue efficiency , where alternator charges depends on driving situation. It suppose to be smart charging, but driving with voltage displayed I'd question its intelligence.
Don't think 2010 come with regenerative charging, but good to confirm what system you have since troubleshooting goes in different directions.
-standart where alternator pumps constant voltage
-regenerative charging, aka blue efficiency , where alternator charges depends on driving situation. It suppose to be smart charging, but driving with voltage displayed I'd question its intelligence.
Don't think 2010 come with regenerative charging, but good to confirm what system you have since troubleshooting goes in different directions.
Trending Topics
MB World Stories
The Best of Mercedes & AMG
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
10 Most Reliable Mercedes-Benz Models You Can Buy Used
Verdad Gallardo
Newbie
Joined: Aug 2019
Posts: 3
Likes: 0
2010 W212
There are 2 kinds of charging systems on W212
-standart where alternator pumps constant voltage
-regenerative charging, aka blue efficiency , where alternator charges depends on driving situation. It suppose to be smart charging, but driving with voltage displayed I'd question its intelligence.
Don't think 2010 come with regenerative charging, but good to confirm what system you have since troubleshooting goes in different directions.
-standart where alternator pumps constant voltage
-regenerative charging, aka blue efficiency , where alternator charges depends on driving situation. It suppose to be smart charging, but driving with voltage displayed I'd question its intelligence.
Don't think 2010 come with regenerative charging, but good to confirm what system you have since troubleshooting goes in different directions.
MBWorld Fanatic!
Joined: Jan 2009
Posts: 9,224
Likes: 1,798
From: V E G A S
1922 Ford Model T / no OBD
12.6V is battery voltage, what would indicate no charging at all.
I would start troubleshooting from scratches:
-display car voltage on the cluster and note it
-turn all the headlights, blower and rear defroster on and then note the voltage change
-start the engine and note voltage change.
-rev the engine and note if the charging voltage changes.
That applies to older charging system.
I would start troubleshooting from scratches:
-display car voltage on the cluster and note it
-turn all the headlights, blower and rear defroster on and then note the voltage change
-start the engine and note voltage change.
-rev the engine and note if the charging voltage changes.
That applies to older charging system.
MBWorld Fanatic!
Joined: Mar 2014
Posts: 3,107
Likes: 394
From: West Central Florida
2011 E550 P2 4M Sedan
You are right, my car is not "blue efficiency". Just tested my old alternator and it was good. I wonder what else could be causing 12.6V while running unless as @thefisch said, it's normality for the W212 in which case it's still an issue because the battery seems to be constantly under-charged.
MBWorld Fanatic!
Joined: Mar 2014
Posts: 3,107
Likes: 394
From: West Central Florida
2011 E550 P2 4M Sedan
Newbie
Joined: Aug 2019
Posts: 3
Likes: 0
2010 W212
Thanks, guys, I really appreciate your input!
The cluster displays 11.9 to 12.2V (depending on whether I've driven the car right before)
Goes down 0.1-0.2V under load
Goes up to 12.6 when it's started, and does not really change (0.1V the most) when I rev the engine
Can you please clarify, are we talking about 12.6V as normal for idling, or for driving as well? Mine is showing 12.6V whether idling or driving, BUT I noticed an amazing thing yesterday - it shows excellent charging every time I put it in reverse or drive in reverse - 13.5 to 14.7V. How would you explain it?
Replaced the starter 2.5 years ago with Mercedes OEM, hopefully, it will last for another couple of years
12.6V is battery voltage, what would indicate no charging at all.
I would start troubleshooting from scratches:
-display car voltage on the cluster and note it
-turn all the headlights, blower and rear defroster on and then note the voltage change
-start the engine and note voltage change.
-rev the engine and note if the charging voltage changes.
That applies to older charging system.
I would start troubleshooting from scratches:
-display car voltage on the cluster and note it
-turn all the headlights, blower and rear defroster on and then note the voltage change
-start the engine and note voltage change.
-rev the engine and note if the charging voltage changes.
That applies to older charging system.
Goes down 0.1-0.2V under load
Goes up to 12.6 when it's started, and does not really change (0.1V the most) when I rev the engine
Yup, 12.6v output was 'normal' for the fuel saving alternator at idle. Eats batteries to save some fuel. There are other threads where folks got similar results. As KEY08 suggested, if your car is taking longer to start, it could be an early sign of the starter going or just showing its age.
Replaced the starter 2.5 years ago with Mercedes OEM, hopefully, it will last for another couple of years
MBWorld Fanatic!
Joined: Jan 2009
Posts: 9,224
Likes: 1,798
From: V E G A S
1922 Ford Model T / no OBD
Often cluster shows 0.5V less than the charging system gives, so assuming that is the case here, 13.1V on battery clamps is low charging.
Meaning your new alternator is not delivering.
But then
Can you please clarify, are we talking about 12.6V as normal for idling, or for driving as well? Mine is showing 12.6V whether idling or driving, BUT I noticed an amazing thing yesterday - it shows excellent charging every time I put it in reverse or drive in reverse - 13.5 to 14.7V. How would you explain it?
Last edited by kajtek1; Aug 26, 2019 at 05:52 PM.
MBWorld Fanatic!
Joined: Mar 2014
Posts: 3,107
Likes: 394
From: West Central Florida
2011 E550 P2 4M Sedan
Can you please clarify, are we talking about 12.6V as normal for idling, or for driving as well? Mine is showing 12.6V whether idling or driving, BUT I noticed an amazing thing yesterday - it shows excellent charging every time I put it in reverse or drive in reverse - 13.5 to 14.7V. How would you explain it?
If you had insufficient voltage from an alternator, then you'd see all sorts of gremlins while driving. The fuel sipping alternator just keep batteries at a low state of charge.
MBWorld Fanatic!
Joined: Oct 2010
Posts: 5,141
Likes: 1,293
From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
My 2010 E550 has been starting like the battery was weak, battery checked out fine, but then the charge was showing 12.6 running, so everyone said it's the alternator that's not changing the battery enough. I changed the alternator yesterday and it's been showing the same 12.6, so I started looking for a different solution and found this post where you say that this voltage is sort of normal for the W212. Can you confirm it, how is your car starting?
A simple test for charging. On highway speed slow down either by just letting gas pedal off or even apply brakes. If you know how to display battery voltage on Comand screen you can see how the steady driving 12.6-12.7 volts jumps up to even 14.5 V.
Even easier test, put your rear fog light on and be amazed how the voltage jumps up to one volt higher.
Your problem is the starter. Replace it and no more problem.
