rb23lb

Hi there - its been a while since I posted here in the W204 forums (got married and had a few new jobs with less time and also a GLK for wife has been more priority than my old trusty w204 recently).

Anyhow, last time I drove my C350 was mid May about 30 days ago. It totally worked fine and normal (only has 45K miles) and perfect as far as I am concerned. I came back to it this morning to start driving it again and it was completely dead. No electricity or lights anywhere in the dash or car turned on, and turning the key was absolutely silent, no attempt at turning over or even hearing the starter make a noise.

I assume my battery is dead, because I have never replaced it since purchasing in Fall 2007 brand new. And I am guessing that some of my splice jobs (ie 4 illuminated door panels) are secretly sapping electricity while the car is off, and if I don't drive it, maybe thats what eventually kills the battery

But regardless, how do I remove the batter and fix it? Is there anything special to do ? The only battery and only other car I have ever drove is my 1984 volvo 240 dl where the battery is right smack in the open as soon as you pop the hood.

If this is a battery issue with the c350, once I remove the plastic battery cover I think that must be covering it, is it safe to jump like a normal dead car?

Or is there anything special with benz that you can screw up or fry by attaching jumper cables to a car from another car?

Just wanted to double check here first in case there are any special procedures I should be aware of.

I know, pretty lame to ask this even, but I have never had this car "die" in the almost 8 years I have had it (been an awesome car), so I just want to check in to see if there are any special tricks or anything.

Thanks in advance for any help that can be provided!

RB

Carsy

If you have a :-

- multi meter you could check the voltage across the terminals.

- battery charger you could charge it up.

Otherwise call a mobile battery person & replace with a Absorbed Glass Matt AGM battery of about 70 to 100 Amp Hours.

Good luck.

babyboxer1

The battery itself is located below your heater fan assembly, which is on the top lefthand (passenger) side of the vehicle. You have to remove the three clips from the heater fan assembly (which are located against the firewall), remove the housing and your battery is right below.

Including a picture of page 452 of my digital owner's manual from a C350. It includes the battery location and recommended jump start procedure. I replaced the battery from my 2008 C350 in March after it wouldn't start following a tire appointment, where the mechanic had the radio running for 10 minutes. Yours being a 2007, seems about time to have it replaced and any MB dealer and most auto parts stores can test it out for free if you remove it and bring it to them. I ended up replacing mine at the dealer with an OEM one for $239-ish Canadian. The reason I went straight to MB was because sometimes aftermarket might vary in size/amps/CC, etc and I noticed the extra ventilation hose that I've never seen before. To me anyway, they're fairly complex vehicles, so I just keep everything OEM as much as possible. Good luck!

babyboxer1

Sorry, don't mean to flood your post with images, but hopefully this helps

C300Sport

I was in your same position a couple months back as I travel a good bit. I decided to use a $50 gift card to buy a new MB battery and now use the old one as a bench test battery...it seems these big ol' MB batteries have a pretty good lifespan.
Did you manage to get your old battery charged or did you replace it?

Carsy

What happened?.

rb23lb

thanks carsy -how long on average do the factory batteries last?

rb23lb

great tips thanks - mine is a 2008 c350 as well but it was delivered in october 2007 . ill look online and if not than dealer stealer

i will update as soon as i resolve

thanks again

babyboxer1

Good luck, hopefully it's just the battery - for a 2008, you were due for a battery soon anyway.

In response to your question about longevity, you could expect 7-8 years out of your battery. It's what I got out of mine, and when it happened, I was actually thankful I wasn't parked in a garage and was able to drive it straight to the dealership. In your case, you can dismount the battery and take it with you to the dealer - they will test it out for free and confirm whether or not you need to replace it.

Carsy

Mine is nearly eight years old now . I have hear on this forum that they can often last over 10 years if looked after .

JimPap

What can you do to make it last over 10 years?

Carsy

Hello Jim,

Live in a mild climate , park under cover to avoid the worst of the heat/cold , avoid it going completely flat & keeping the engine in a state of easy start would be four .

In lead acid batteries keeping the level above the plates would be #1.

HawaiianC350

Personally, I'd call the free mercedes road side assistance service.

Yesterday, my car wouldnt start, but it had power. The road side assistance showed up and started it in a second. Apparently, my steering wheel was too tightly turned. I just gave him a few bucks for tip.

rb23lb

I am going to call Mercedes Roadside assistance today (home from work finally). I had no idea I still qualified out of warranty, but good to know I still do since I purchased direct from a dealer.

How much should I expect to pay at a dealer in the US for a new battery? And I assume 100 Amp hours is better than 70?

Are there any noticeable performance declines if I purchase a 70 amp hour battery as opposed to a 100 amp hour?

babyboxer1

I paid no more than $250 CND for an original battery from the dealer. I replaced it myself, so the price was just for the battery. With current exchange rates, I'd estimate your battery to be about $200 USD. Don't be shy to call the parts department at your local MB dealer to ask for a quote and whether they have one in stock for you.

I kept everything original in terms of specs - I'm no expert, but I've heard a bigger capacity battery sounds nice, but it may also put a bigger strain on the alternator. I got 7+ years out of my original battery, and I was happy with that.

Carsy's advice is probably the best, as I've seen a couple of posts that "it can last 10+ years if you take care of it". I live in an area where temperatures can dip to -40 in the winter, and +35 in the summer. That's not ideal for the life of the battery, but I also never got more than 5 years on a battery in my previous vehicles, so I was more than happy with what I got out of my MB's battery. If your winters are rough, then probably make sure you don't go more than a day or two without starting the car and let it reach operating temperature, which can be 12-15 minutes for me.

Carsy

My diesel has a 70 amp hour capacity but I do notice that your cars in the US have 100 amp hours batteries.

I think it depends on the number of extra auxiliaries you have or attach .

Colder climates probably need a larger battery.( more torque needed to turn a cold engine)

Make an executive decision yourself