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2014 E350 station wagon gasoline
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Discussion Starter #1
I bought a very low mileage E350 two weeks ago. It's MY 2013 (November) but it is the face-lifted 2014 model.
I has 17k miles on it so the previous owner barely drove it (less than 6k per year).
I worried about the battery's condition so I checked the voltage the morning after I got it home. It showed 11.80 volts. I put it on a float charger and charged it for two days.
I checked the voltage again and it was 12.26V.
I have been driving it almost every day since, about 50-70 miles a day, and the resting voltage is never above 12.3 volts.
The alternator puts out about 14.7 volts so it is working fine.
I googled it but couldn't find any information as to what would be a fully charged voltage for an AGM type battery. Lead acid batteries are around 12.5 - 12.6V when fully charged.

I recall a thread here where it was reported that these type of batteries are only charged to abut 80% of their capacity when charged by the alternator in the car however that would be only about 10.8 volts.

So my question is, has my battery suffered sulfation because of being undercharged for 3 years or is this voltage (12.26V) normal for this type of battery?
The battery is sold on amazon.jp for 27,300 yen which is about $250US in case it gives up on me suddenly, as some owners have reported it.
 

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'85 300D Turbo, '91 420SEL, '92 190E 2.6, '09 C350, '12 E63 Wagon
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I expect an AGM to have the same voltage as a regular lead acid. (Someone can correct me if I'm wrong). I keep mine on a charger for a long long time while it is at home. It gets very very little use. When I do drive it the next day or two I will usually put it back on the charger. When I do the Schumacher charger that I use shows the voltage, and the lowest I've seen is in the low 12s, maybe 12.3 like you noted. So I believe the charging system does seem to keep the battery at around 12.3 V like you are seeing. If I recall correctly this corresponds to about 80% charge, (my charger also will show the % charged).
 

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'04 G55 '80 280GE '99 S420 '98 E320 2011 E350 2016 GLA250
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dacia, 'Kon-bawa'

Dunno' if this thread will help you, or not:

http://www.benzworld.org/forums/w212-e-class/2509617-interesting-w212-battery-charging-system-factoids.html

If you want, you can go into the 'ASSYT' section of your Display, and actually Monitor the Charging state.

Of course, if you are concerned, at all, of the Overall 'Health' of your Battery? Find a battery vendor who can do a "Load-Testing" (a Midtronics unit is Preferable). This will instantly tell you the Condition of your battery.
 

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2014 E350 station wagon gasoline
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Discussion Starter #4 (Edited)
Thanks G-AMG.
I read your other post before I wrote mine, I just hoped to hear from other owners if they had the same experience.
However, if your supposition is true why wasn't the battery fully charged after I left it on the float charger for two days?
It's supposed to be a fairly good charger (NOCO Genius G3500 6V/12V 3.5A) that can monitor the battery voltage and adjust the charge accordingly.
So it might still be possible that the battery is weaker than it should be because of lack of driving by the previous owner.
I guess I shouldn't sweat it, just keep an eye on it.

By the way it's konbanwa. :)

Your DIY posts are epic, I used them many times when I had the W210.
I hope you'll have time to make the same ones for the W212.
After looking around the engine bay it seems rather involved just to even change plugs (the engine in the 2014 model looks different from the 2010-11, even though they are both the M276 I believe).

How do you get into the "ASSYST" section, I don't seem to have the option on my display. It may have been removed after the facelift.
 

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2014 E350 station wagon gasoline
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Discussion Starter #5
Never mind, found the DYNO mode. Call button + OK button on steering wheel, hold for 5 sec.
It shows battery voltage 12.1V engine off and 14.8V with engine running.
 

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E320/E250 Bluetec Ford F350 6.7l
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Never mind, found the DYNO mode. Call button + OK button on steering wheel, hold for 5 sec.
It shows battery voltage 12.1V engine off and 14.8V with engine running.
None of those readings are good, but car display often change the actuall reading.
Confirm with independent voltmeter.
Battery should keep at least 12.5V measured at least 12 hr after charging (engine running).
The charge system should not exceed 14V for long period, or it will shorten battery life.
 

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2007 S550 4matic. 166k-1987 560SL,111k
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The only way to know is to disconnect the battery and charge it properly overnight. Then let it rest overnight (disconnected) and check the battery's voltage then with a proper meter. shouldn't be below 12.6 at this point. 12.5 is suspect and anything lower I'd replace it.
 

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2014 E350 station wagon gasoline
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Discussion Starter #8
Well, I checked it many times after sitting overnight and it is consistently around 12.2 volts.
I guess I won't sweat it anymore, it is what it is but I can tell you I will definitely not "replace" it just for being a bit under voltage.
I'll replace it when it dies, it would be a total waste of money throwing it away after 3 and half years.
 

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2007 S550 4matic. 166k-1987 560SL,111k
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Sitting overnight connected to the car or disconnected?

connected = something on car draining it overnight or self discharge
disconnected = self discharge.



Well, I checked it many times after sitting overnight and it is consistently around 12.2 volts.
I guess I won't sweat it anymore, it is what it is but I can tell you I will definitely not "replace" it just for being a bit under voltage.
I'll replace it when it dies, it would be a total waste of money throwing it away after 3 and half years.
 

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'85 300D Turbo, '91 420SEL, '92 190E 2.6, '09 C350, '12 E63 Wagon
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Just as a reminder newer cars have start stop implemented using the battery only at temporary stops, ie stoplights or stop signs.
 

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On my e320 bluetec there is a 25 Amp draw upon unlocking the door than will go down to 1 Amp. Volt 12.1 at battery terminals. The e350 draw unknown but goes to 12.3v. Both agm batteries are 7 years of AGM batteries. Size H8/49 with 2 years in AZ hot summers and 47/48 in nyc respectively. Battery tester has passed specification. Time to replace the H8 one? SOC 60% , SOH 65%. On line ordered at Pepboys 25% off and $40 rebate, so about $110 after rebate.
 

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The rebate expires on the 24th. Sales date is when battery is picked up. $110/$200 is s great price. Bosch batteries are no longer carried by Pepboys.
But what about the soc now at 12.46v and 571 out of 850 cca in an e320 with high capacity alternator?

Also on the e350 has an H7 760 CCA battery. Will an H8 900 cca battery overload the alternator ( Reg. Alternator)?
 

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2008 E350 4Matic, 2011 E350 4matic
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I thought it was an H6 battery. Anyway, the question is more of whether it will fit. People put in bigger batteries all the time. You can't overload the alternator by putting in a bigger battery, it just takes slightly longer to charge that's all. As for the lower CCA, most alternators don't fully charge up the battery. You can put it on a battery charger to get it more fully charged up and that will probably make the battery last longer.
 

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The e350 can take an H8 battery. The c350 can’t take the H8 battery. Any computer charging reset needed?
I will use a jumper battery to maintain the old settings.
 
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