2010 E350 4Matic
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E350
2010 E350 4Matic
I have a 2010 E350 4Matic with 40,000 miles on the clock. I have had two alternator failures in the last two weeks. Only puts out 12.2 volts. Should be 14.7. My dealer is scratching their heads on this problem. Anybody else have experienced this issue?
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From: West Central Florida
2011 E550 P2 4M Sedan
I've only seen my alternator output 14.7 volts just after starting up. Then is outputs 12 point something volts. There are posts on here suspecting that it was designed that way to save on fuel consumption while putting more strain on battery life.
But the fact that your dealer has replace it must mean it failed some kind of test. What did they say was normal output?
But the fact that your dealer has replace it must mean it failed some kind of test. What did they say was normal output?
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From: West Central Florida
2011 E550 P2 4M Sedan
In experience in other cars, bad alternators have resulted in loss of power while driving. Haven't had the experience in an MB (yet) so I don't know how a bad alternator would act. What symptoms were you having that lead you to get it checked out?
Before I replaced my battery, I was checking voltage pretty frequently. Here is a good thread if you want to check it (as measured by comand) while driving using engineering mode https://mbworld.org/forums/e-class-w...e-problem.html
While driving, my car was reading 12.6 volts. I have had my charging system tested and never got a failure on the alternator. The assumption here is that these cars try to smart charge the battery and only increase alternator output when needed. My wife's Honda outputs 14 volts all the time.
Let us know what your dealer finds. While I have assumed my alternator was normal, it may really not be.
Before I replaced my battery, I was checking voltage pretty frequently. Here is a good thread if you want to check it (as measured by comand) while driving using engineering mode https://mbworld.org/forums/e-class-w...e-problem.html
While driving, my car was reading 12.6 volts. I have had my charging system tested and never got a failure on the alternator. The assumption here is that these cars try to smart charge the battery and only increase alternator output when needed. My wife's Honda outputs 14 volts all the time.
Let us know what your dealer finds. While I have assumed my alternator was normal, it may really not be.
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E350
No lack of power. Car would just not start because of low battery. Once I jump it no problem starting. Just as a test, left parking lights on for 20 minutes and tried to start. Battery dead. Meter indicated 10 volts. Battery is 3 months old and checked out okay.
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From: West Central Florida
2011 E550 P2 4M Sedan
Sounds like my experience before I replaced my old battery. In fact, battery tests showed the old battery was good but needed charging. It would die under normal use every 4-6 weeks so I finally gave up on it. But that was the OEM battery that was 4.5 years old.
I've had a new battery for 9 months with the same alternator readings and it's held up fine. Where is you get your new battery? Is it an AGM?
I've had a new battery for 9 months with the same alternator readings and it's held up fine. Where is you get your new battery? Is it an AGM?
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MBWorld Fanatic!
Joined: Mar 2014
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From: West Central Florida
2011 E550 P2 4M Sedan
So are they testing the battery and telling you it's good but the alternator is bad? 12.2 volts is lower than what I am seeing.
And was the O'reillys battery an AGM (absorbed glass material) SLA battery or a regular SLA battery?
And was the O'reillys battery an AGM (absorbed glass material) SLA battery or a regular SLA battery?
MBWorld Fanatic!
Joined: Mar 2014
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From: West Central Florida
2011 E550 P2 4M Sedan
Looks like their platinum super start is an AGM version. Maybe they sold you that one. I could see how a regular (non AGM) SLA like their super start extreme could have problems with the low state of charge that the low output alternator my car seems to have. I am no battery expert, but I've read that the AGM SLA batteries are better at handling deep cycling where they are kept at a lower state of charge.
In your case, 12.2 volts sounds too low. But after two alternators, what else are they going to try?
In your case, 12.2 volts sounds too low. But after two alternators, what else are they going to try?
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E350
Good question as to what they will try next. I told the dealer to keep it until it is fixed. The service tech is driving it for a few days. In the mean time I'm driving their C300 loaner. What a difference between a C Class and an E Class!
