Hi folks,

My wife’s 2009 C350 (17K miles) started to have problem when starting the engine last week. It was kind of when we twisted the key, the starter turned normal for the 1st second, and then the starter had a weak/slow turn at the 2nd second, and the engine started at around the 3rd second.

It was like that for the last few days.

Today, when we tried to start the car, the starter cranked for one second, and then it wouldn’t turn again. I removed the key, opened & closed door, reinserted the key, and tried to start the engine again. No luck.

I tried a few more times, and the lights at the dash cluster would even turn dim and the Command LCD screen would stop half way open/close.

I grabbed my portable battery charging station that I bought from Costco, and tried to jump start the car. The engine started right up. I let the engine run for a few minutes, turned off the engine, and then I could start the engine without needing the portable battery charging station again.

Folks, I guess this is a classic example of a bad car battery, am I correct?

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The reason I ask help from you folks for troubleshooting is that… The car is just two-years new, and my wife drives the car every day. I guess nowadays a new car battery (even an OEM Mercedes one) would last more than two years? Or it is a hint of something else is wrong in the car that caused the weak battery problem (any known recalls)?

I am going to bring the car to the dealer first thing Monday morning, and would like to arm myself with knowledge from you folks. It is because I wouldn’t want my dealer just send me home saying everything is alright but later the problem repeats. It is my wife’s car; hence I really hope to make sure that she won’t get strangled in the middle of day on the road.

Many thanks, and with best regards,

- Alex.

 

It could be the battery not holding the charge, but on the other hand, the charge may not be getting to the battery (voltage regulator, electronics). The alternator works because the car has full power once you boost it and get it going.

 

When my 2009 C300 went in for a A service, the tech found a weak cell and replaced the battery under warranty before it failed. Perhaps our batteries were from the same production batch with a similar issue. In any event, a new battery should be fairly quick and easy under warranty.

 

Thanks folks, for all the advises,

I forgot to mention that the car just had a Service B1 done about three weeks ago at the dealer. At that time, the car ran flawlessly, and the service report didn't mention any abonormality.

On the Service B1 paperwork, the tech did check the item:

• 'Battery (Main/starter/auxiliary) check condition using "Midtronics MCR717" tester. Attached Midtronics MCR717 Test Report print out here.'

I couldn't find the MCR717 Test Reprot from the paperwork, and frankly I doubt the tech did actually perform the test on the battery. Assume if the tech did check the battery and it was okay, could a battery fail within three weeks? Or is it a hint of something else?

Sorry, I couldn't bring in the car to the dealer until Monday, hence meanwhile I just hope to prepare myself with all the knowledge.

Thanks again,

With best regards,

 

MB will check the battery voltage with the engine running. It should be about 14 volts if all is well with the alternator system.

It sounds very likely that the battery is failing.

You could also have an earth on your system which is draining the battery when the car is parked. Also make sure that you have not left any electrical equipment in service when the car is not in use.

Good luck on Monday, Keep us informed of the outcome. A replacement MB battery for my car is $800 in Australia. !!

 

Probably a bad battery. Should they last more than 2 years? Sure. Might they fail before that? Sure.

Note: It could (though unlikely) be some odd current draw discharging the battery. My BMW 750i had a strange problem where the keyless entry module in the driver's door was drawing an abnormally high current draw when the car was turned off. It showed up on an extended current/load test overnight.

 

It's the classic symptoms of a bad battery. The alternator turn-on speed is engine crank speed or less - so don't have concerns about the charging system just yet.

All parts have a defect rate - when a part fails is far from predictable with very little rhyme or reason. You'll get a battery under warranty or at least pro-rated. What I wouldn't do is to continue to drive the car with a defective battery and cause the alternator to become a constant battery charger.

 

a portable jump box to jump an MB.
You can toast the DAS circuit.
You can use a box charging station to charge the battery via the charging post under the hood for several minutes but don't use it to jump the car.
Are you still under warranty?

 

It sounds like a typical defective battery, but it could be a defective starter, a cable, a wire a module, good thing you car is still cover under WARRANTY.

 

Thanks again folks, for more inputs.

Yes, my car is still under warranty, and I hope it is just a bad battery. In Monday morning I would also ask the dealer to check for any possible battery drain or possible fail to charge, and hope they can find out easily if so.

And a good advise not to drive the car for now, because it may be hard for the alternator if the battery is bad. I will just jump start (correctly) and drive it straight to the dealer in Monday morning, which luckily is just a couple miles away from my house.

I will keep it posted tomorrow on what the dealer finds out. Wish me luck...

With best regads,

 

Batteries can develop a dead cell overnight. Good today, dead tomorrow.

BTDT.

 

Hi folks,

Just an update:

I brought the car to the dealer yesterday morning. They found that it was the fuse box (the one in the engine bay next to the battery, I guess) which caused a battery drain. They also tested the battery, it was stong and well.

They didn't have the fuse box in stock, so they ordered one and it arrived this morning.

I just picked up the car this afternoon, the new fuse box was in place and everything seemed to work okay.

Thanks folks, again, for all the advises and inputs. I really appreciate them.

With best regards,

 

Thanks for the update.JC

 

Just curious,
If the battery was pretty deeply drained, how much damage could that do to the longevity of the battery? Just thinking that if you really deeply cycled that battery too often with an issue like this, you would be looking at replacing that battery much, much sooner than otherwise.
Does MB offer new batteries for some situations like that?

 

Good question -- I believe it will probably have some effect, more or less, on the longevity of the battery itself?

Yesterday I did ask the service advise at the dealer that how much would a new W204 OEM battery cost nowadays, he said it is about $195 plus labor.

In my case, the C350 is my wife's car that she leased under her business, and the lease has one more year left. She will be replacing the car with another new Mercedes (she likes Mercedes) after that, probably the 2012 C-Class sedan or coupe.

With best regards,

 

This morning my car wouldn't start either. I left the sidemarker on overnight (accidentally) and when I tried to start the car I would not start up. Headlights would not turn on either. On the display it indicated "SRS Malfunction, Service required".

I then charged it with a battery charger for about 30 -45 minutes and still would not start (maybe not long enough). I then called MB roadservice and the tow truck came with a portable device and got it to start.

I usually dont leave the side marker on overnight, but since that is designed for that purpose, I didnt expect that two light bulbs would drain the battery that quick?


How would a defective fusebox lead to battery drain?

 

since when are side markers designed to be left on overnight?

im surprised that the MB doesnt have an auto shutoff to prevent the battery from draining. On a Toyota, after 30 minutes of inactivity, all interior and exterior lights turn off

 

My 2011 is has these exact problems as the OP mentioned. This morning the car displayed "SRS Malfunction" I hope the issue is as simple as replacing the fuse box.

Can anybody tell me what "Tips document GI54.10-p-053760" would refer to? it was mentioned on the service sheet.

 

Dropped of my car on Saturday and was told that they could not diagnose where the problem was and I had to remove my aftermarket items before they would go further. in addition to that I had to pay for $210 diagnostic fee because it was not considered to be part of the warranty...

Removed all after market stuff on Sunday and dropped it off this morning. called MB up and they told me it was a dead battery. not sure why they could not detect that on Saturday........

Anyway, just wanted to give an update what the root cause was.

 

Thank you.

 

Hmm..
My 2011 C250 also failed on Batt not too long ago. With the Batt drained to that low level, it would get damaged. Our problem was that it was almost like a weekend car. It was hardly driven. It gets driven more often these days. Any how, after much consultation with the Merc dealer, they decided to change the batt under warranty. From my understanding, if the batt have gone flat once, it will only be able to charge 50% or less of the capacity.

Here is one of the link that I found about battery. Even in this article, it says that "no amount of driving will recharge a discharged battery."

http://www.racq.com.au/motoring/road.../battery_myths

Hope this helps.

joe....

 

17,000 on a 2009 leads me to belive she may make short trips, especially since you said she drives it every day. Nothing will kill a battery quicker than short trips. I was on the BMW forum and someone had the same experience. The dealer coulsactually determine that he was making short trips, draining the battery due to many starts with no enough run-time to fully charge it.

 

I am at 35000KM which is about 22000 Miles and drive about 20 min per day so that could be. None of my other cars (including 2008 C) have had a battery replaced in such a short time. but it happens I guess.

My main disappointment is mainly with the dealer as they could not diagnose it until the second visit and having to remove all aftermarket items.