lee16

I have a 2010 e550 and I've noticed it takes longer to start. I'm thinking the battery is going...anyone know how long a stock battery will last? I appreciate your help.

CEB

There are many variables to how long a battery lasts. If a car is garaged when not driven, driven regularly, driven for longer trips only (10+ miles) and not allowed to run down, the 6 or 7 years is quite do-able.

Short trips, letting the battery run down and leaving the car exposed to temperature extremes can kill a battery in a couple of years. Just one time of letting a battery run down is enough to cut its life in half.

Anakclk

My car is 2010 E550 coupe. Last month, I noticed it took a little too long to start for many times. Then, I wouldn't start at all. I went to a dealership and they said the battery is bad and replaced it for free. I think you should go to a dealership to have your battery checked because last time when my car wouldn't start, it took almost one hour to find jumper cables.

threeMBs

2010 battery "issue" is known to Mercedes. On my 2010, 2.5 years old, 17K miles, battery was replaced free of charge (labor and the battery itself) and under warranty by MB roadside assistance two months ago. Car was dead, called MB roadside. Local MB dealer "picked up" a call and already had a battery with him. Said its a common issue with 2010 cars. They're replacing them completely free of charge (under warranty) when they fail within 4 years/50K miles.

The way he explained it to me was that it is not the "bad" battery, but a fan that stays on for too long after car is turned off (software problem that does not shut that fan on time, which was resolved after 2010) and in time degrades the battery causing it to fail. Obviously doing a recall is too costly (since not all cars are failing), but on those that do, they replace the battery.

lee16

Thanks I'm taking the car in as suggested. Did they fix the software problem?

threeMBs

My battery was replaced by the roadside. To upload new software, car needs to be taken in, which I did not do yet.

Arrie

What fan are you talking about? I have a 2010 E550 and I have never heard any fan running if the car engine is OFF. Not even when it is very hot day and engine has run hours before I shut it OFF.

threeMBs

I've never heard any fan either, but that's what he told me (he would not go into details, just stated nothing needs to be changed except some software needs to be flushed). The bottom line is, MB is replacing 2010 W212/C207 batteries free of charge when they fail or about to. He did not even check the battery, just tried starting the car, then immediately replaced the battery. He already had it with him as it was happening to too many 2010 Es to be a one off.

Live Oak

Per my dealer, who had to come out and start my 2011 E550 at 18 mos., 23,000 miles (Roadside Assistance), the problem is the AC evaporator drying fan ~sometimes~ running when it shouldn't --- all night!. You will hear that fan running, starting about an hour after stopping the car, and for a half hour or so, when the AC had been running.

In my case, however, the tech not only updated the software, he did me a favor and turned off the "drying" feature. Many miles and months later, the AC began to stink of manure when first started. The dealer turned the feature back on and informed me the the tech is no longer a Mercedes employee.

threeMBs

I think that's about what he told me too.

lee16

Thanks everyone for your suggestions. Does anyone know how strict Mercedes is when it comes to appointments. Its Sunday today and the next available appointment is Tuesday :/
Can I just bring it in first thing in the morning without an appointment?

CEB

Depends on your dealer - not Mercedes.

mikeyle

i hear my fan on all the time, its not quite loud but in a garage its very noticeable about 45 mins after the car is off, mine is a 2012 350

Live Oak

As long as it doesn't run all night, that's great.

pdjv

Some W212 models have a "REST" button one can press to run the HVAC fan at low speed after the smart key is removed to keep the interior warm by circulating residual engine heat or (in warm weather) help avoid a musty odor by drying the A/C evaporator.

According to the PDF owners manual "It is possible that the 'residual heat' function may be activated automatically an hour after the SmartKey is removed. The vehicle is then ventilated for 30 minutes to dry the air conditioning system." Sounds like early W212 cars may have had a software glitch that let the fan run way longer than 30 minutes.

The manual doesn't make it clear so I'm guessing cars without a REST button still have the automated A/C drying feature.

BenzV12

I first turn off the A/C and then stop the engine and I have never heard of my fans running ,may be by doing like that I am eliminating the possibility of fans kicking in by itself

mikeyle

i do the same thing, check on your car an hour after you shut it off, the fan doesnt start running until a while after you turn the car off

Live Oak

I guess my question is: Why do you turn off the AC?

mleskovar

I've been closely monitoring my car's battery health since I bought it 7 months ago and come to the conclusion that the "smart charging" doesn't keep the battery at full charge....ever. I've installed an easy hook up for a battery tender and now fully charge it monthly. Left on it's own the battery stays between 25 and 50% charged no matter how much you drive and the more you drive doesn't necessarily mean it will be closer to 50%. It goes from full charge down and never recovers to full unless force charged. I've checked the charge status before and after the AC evaporator cleansing operation and it didn't discharge the battery much at all so I don't think that's the culprit. My last Benz battery constantly stayed fully charged as long as I drove it consistently. This one....no. I wonder what the thinking on this is?

BenzV12

Mechanics, tech guys whom I talk to and car mags I read recommend to turn off A/C to get car to start easier and extend the lifespan of the A/C compressor and not to mention A/C compressor draws too much juice by default

pdjv

How are you measuring the battery's charge state? If you're using a simple VOM with the battery connected, you may not be getting accurate results.

mleskovar

Lead acid battery charge can be measured with it connected and a DVOM. You can't measure cranking amps, only % of charge:
12.68V = 100%
12.45V = 75%
12.24V = 50%
12.06V = 25%
11.89V = 0%

lee16

My car wouldnt start and it wouldnt crank at all but the lights on the dash worked. I took it in to the dealer and they discovered that the starter was bad. Replaced for free.

El Cid

The best or nothing!

pdjv

Ok, but here's an extract from Battery University on measuring state of charge.

"When measuring SoC by open circuit voltage, the battery voltage must be truly 'floating' with no load present. Installed in a car, the parasitic load present makes this a closed circuit voltage (CCV) condition that will falsify the readings. Adjustments must be made when measuring SoC in the CCV state by including the load current in the calculation. In spite of the notorious inaccuracies, most SoC measurements rely on the voltage method because it’s simple."