W212 Battery

[Aston Dabb]

Hi everyone,

I’ve bought an MB AGM battery for my fathers E350 W212 Estate but his car is a 2010 without stop/start function; and for that reason I assume his won’t have an AGM battery so would it be ok to fit an AGM battery? I’m replacing due to it idling high and everyone thinks this is due to a weak battery (ECU increasing idle to help alternator). Thanks

 

[Roxie]

It will have a vrla battery. But it will be okay if is the right ah.
It could be why it is idling fast. But it could also be due to additional AC demands.

 

[Aston Dabb]

It will have a vrla battery. But it will be okay if is the right ah.
It could be why it is idling fast. But it could also be due to additional AC demands.

@Roxie it only seems to idle high when the ambient Temperature is low and heating is ON. When you turn the heater or climate control off and give it one rev it’ll drop back down to 600idle but soon as you turn it on it’ll idle at 800. Doesn’t seem to do this when it’s warm weather though? When I last plugged it into Xentry (as EML came on), it came up with 101B00; The signal of sensor 1 of component ‘B37 (Accelerator pedal sensor)’ is too high. That fault was in ESP & CDI; but when you rev it and the rev drops back down you’ll see the display on the rev counter dim and brighten (flicker) ever so very slightly for a split second?

 

[Roxie]

There is a PTC heater in the cabin heater this also can have an effect on engine idle speed so it could be a normal function. The accelerator pedal contacts could be dirty giving this fault code. But I don't think this would affect the idle speed

 

[Aston Dabb]

There is a PTC heater in the cabin heater this also can have an effect on engine idle speed so it could be a normal function. The accelerator pedal contacts could be dirty giving this fault code. But I don't think this would affect the idle speed

@Roxie i am going to fit new AGM battery today and replace accelerator pedal. Do you have to programme new battery in?

 

[malcolm E53 AMG]

If the battery is the original it is very likely the cause of the problem MBs don’t like under voltage batteries a healthy battery should read 12.6V engine off and 14V+ engine running I generally change my batteries at 7 years old to avoid problems

 

[Roxie]

No.
I think the pedal will work fine but I believe it can be callibrated with star.

 

[AMGeed]

@Roxie i am going to fit new AGM battery today and replace accelerator pedal. Do you have to programme new battery in?

No, no prgramming but you may have to reset the windows.
Ign on P2, open each window in turn on the button down fully, then raise and hold for 5 seconds.

 

[Aston Dabb]

No, no prgramming but you may have to reset the windows.
Ign on P2, open each window in turn on the button down fully, then raise and hold for 5 seconds.

@Roxie @AMGeed i’ve ran it on the Xentry today with no faults but a low voltage fault in the levelling system (Susp) on 30G. I’ve gone into the charging system and when it cranks it goes down to as low as 8V!!! I know this is not the same as a multimeter check but does this confirm battery is bad? Once running it’ll charge at 13.8-13.9v. But the car sits around a lot and I’m just thinking this confirms bad battery and what’s caused the accelerator sensor issue That caused EML in the past as mentioned on first post. It hesitates terrible in drive at 1500rpm but I don’t know if this maybe related due to lack of power supply or a different problem

 

[Blobcat]

14.6 - 14.8 is a good charging voltage at ~2,000 revs. 12.6-12.8 is a good resting battery voltage

 

[Tony Dyson]

Hi everyone,

I’ve bought an MB AGM battery for my fathers E350 W212 Estate but his car is a 2010 without stop/start function; and for that reason I assume his won’t have an AGM battery so would it be ok to fit an AGM battery? I’m replacing due to it idling high and everyone thinks this is due to a weak battery (ECU increasing idle to help alternator). Thanks

If the battery needs replacing, it should be replaced with the same OEM specification, like for like replacement, you will then have the confidence that the charging voltages and algorithms programmed into your ECM/BCM's are compatible with the same technology battery/ies as the OEM designed. If the charging voltages are incompatible and too low, your battery will never reach it's full potential, too high and some VRLA batteries can be permanently damaged, I would first of all contact MB and confirm the original spec battery to be replaced!

 

[Aston Dabb]

If the battery needs replacing, it should be replaced with the same OEM specification, like for like replacement, you will then have the confidence that the charging voltages and algorithms programmed into your ECM/BCM's are compatible with the same technology battery/ies as the OEM designed. If the charging voltages are incompatible and too low, your battery will never reach it's full potential, too high and some VRLA batteries can be permanently damaged, I would first of all contact MB and confirm the original spec battery to be replaced!

@Tony Dyson the old battery is a VRLA battery and the new battery states it is a VRLA/AGM? I assume they’re comparable as it’s the same amp figures as far as I’m aware etc

 

[Tony Dyson]

@Tony Dyson the old battery is a VRLA battery and the new battery states it is a VRLA/AGM? I assume they’re comparable as it’s the same amp figures as far as I’m aware etc

That isn't what you stated in you OP which I responded to, however, my advice is still relevant, any replacement battery should be the same specifications as the OEM's, I would still make that call to MB to confirm the correct spec battery has been fitted previously.

 

[Roxie]

For what its worth I think it is the same battery.
If it states vrla/agm it is not a true agm battery.

Advanced glass mat. Batteries are comparitively much more expensive than valve regulated lead acid ones.

AGM batteries are more for caravan boat leisure.
They can take a lifetime to charge to 90% but don't get damaged if they go flat frequently.

From what you have said drops to 8 volts when cranking I think this is your problem. Most of the control units shut down at 9 volts.

 

[Tony Dyson]

For what its worth I think it is the same battery.
If it states vrla/agm it is not a true agm battery.

Advanced glass mat. Batteries are comparitively much more expensive than valve regulated lead acid ones.

AGM batteries are more for caravan boat leisure.
They can take a lifetime to charge to 90% but don't get damaged if they go flat frequently.

From what you have said drops to 8 volts when cranking I think this is your problem. Most of the control units shut down at 9 volts.

An AGM (Absorbent Glass Mat) battery, and not Advanced as you have mistakenly advised, is in fact one of two types of VRLA (Valve Regulated Lead Acid) batteries, the second having a Gel based electrolyte as the acid component again with lead plates. Additionally, ALL Lead acid batteries suffer damage if left discharged for any length of time.

 

[Aston Dabb]

For what its worth I think it is the same battery.
If it states vrla/agm it is not a true agm battery.

Advanced glass mat. Batteries are comparitively much more expensive than valve regulated lead acid ones.

AGM batteries are more for caravan boat leisure.
They can take a lifetime to charge to 90% but don't get damaged if they go flat frequently.

From what you have said drops to 8 volts when cranking I think this is your problem. Most of the control units shut down at 9 volts.

@malcolm210 @Roxie I had an E220 W212 in today running at around 14.3v (I wanted to check so I could compare to my fathers E350); but my fathers E350 W212 charges at 13.8v (according to Xentry), but yeah voltage does drop on the star drastically when cranked over but the car isn’t used at all and is now 10 years old (assumably it’s on it’s original main battery) but what I cannot understand is you can leave the car for a month and it’ll still start without needing a jump! But it will charge at 13.8v according to Xentry and drops to approx 8V when cranked. When turned off, it’ll rest at around 12.1v. It misfires when cruising also and I’ve read this can be caused by low voltage. Also there are no faults for the PTC Heater mentioned

 

[Roxie]

Charging on these cars is controlled by the cdi or ptcu usually with a lin signal.
Some now are smart charged to save fuel and emissions using the values from the battery sensor.
So a better way to check charging is with a current clamp.
Looking at the voltage on the top of the star is not a valid test. This is reading the value over the diagnostic can and probably drops because the can is shutting down.
Unless the battery voltage is dropping bellow 9volts with the engine running I don't feel this is the cause of a miss fire.
I would have thought 14.3 volts a bit high.
The battery should not go flat if the car is left for a month or even 2 Prety much everything shuts down after around 6 hours.
There are obviously cases where a battery goes flat sooner because of other outside influences.

 

[Roxie]

An AGM (Absorbent Glass Mat) battery, and not Advanced as you have mistakenly advised, is in fact one of two types of VRLA (Valve Regulated Lead Acid) batteries, the second having a Gel based electrolyte as the acid component again with lead plates. Additionally, ALL Lead acid batteries suffer damage if left discharged for any length of time.

My point is that true AGM Batteries are deep cycle batteries designed to be charged and recharged when flat not to be kept topped up.
And that they are much more expensive than other battery types more suitable for use in vehicles.