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Mercedes B200 battery

A friend has been borrowing her friend’s 2008 B200 for a few weeks. She went to drive it today and the battery seems to be dead:

  • the interior lights don’t come on when you open the door
  • the dash display DOES show the odometer and a few other things for a minute or so, then kills it when, presumably, the timer runs out.
  • she can’t start the car. In fact, some solenoid isn’t even engaging to let her turn the key.
  • there’s no power to even open the back hatch.

We couldn’t find the battery while we were looking. Some research afterwards shows me that it’s under the front passenger seat. From what I can tell, there’s no remote positive terminal in the engine bay or under the car. So how are you supposed to boost this thing???

This forum is US-based, and the Mercedes B class is not sold in this country, or at least–not yet.

However, I would advise you and your friend to do the same thing that I would advise somebody in the US to do in a case like this, namely…look in the Owner’s Manual.
Surely the manual has information that includes how to locate the battery and/or remote battery terminals for maintenance purposes.

That would explain why I couldn’t find it on Autozone’s site… strange, they sell them in Canada. You should be glad you don’t have them down there, they’re pretty ugly IMO.
There’s no manual with the car. The owners are away.

The owners took the manual with them on vacation?

Maybe the manual is in the owner’s house. That is also a poor choice to store the manual.

Or it might be in the trunk. I’ve seen owners manuals in the trunk of several rental cars. Maybe in the spare tire area or another compartment back there.

I found that you expose the battery under the seat and jump it at the battery.

Didn’t see it. Well, my friend decided to ride her bike down to the local dealer to ask, so I guess we’ll find out soon enough.

@knfenimore do you need to pull the seat? Do you have a link?

Here is a link to the ineractive manual.

Sometimes you can boost / charge it through the power-port formerly called a cigarette lighter. Current must be limited to 15 or 20 amps…You may need to make up a plug adapter to connect to a battery charger and plug into the lighter socket…It will take a few hours at this low charge rate before the car will start…Should you try this, be SURE to maintain the correct polarity. If the battery is shot, this will not work as the battery will not charge…

What I would be concerned with would be if there are problems which the owners of the car may lay at the feet of the person who borrowed the car.
Getting involved in this also puts your fingerprints on it. Hopefully there are no issues; just saying…

Indeed, I’m a little bit nervous about jumping it, even though I know what I’m doing. In the end, she called the auto club, they came with a jump pack, found the battery, boosted it, car started right up. Turns out the battery is under the passenger side front carpet and mat. Who knew?

No explanation as to why the battery ran down after being parked for 5 days. Buddy didn’t stick around to check much. I’m waiting for a call that my friend is broken down on the other side of town while driving to charge the battery again.


If this is still the original battery, it’s about time for another one

And if it keeps dying after that, somebody needs to perform a parasitic draw test and test the charging system

If you do this, you’d better be getting at least a steak dinner . . .