smikes19

My in-laws have an 08 c300 which isn't exactly new, but its less than a year old. They didn't drive it at all last week and the battery is completely drained.

Are there any basic things to check for? At least in my 09 c350, you can't leave the lights on accidentally since they will shut off automatically after a few minutes...

They took it to Beshoff of San Jose and some guy gave them crap about how all C-classes will go dead if not driven for 10 days. Then he was like, yeah, we charge up the batteries in the cars on the lots!

I don't quite buy that...

drevil2k2

Although a different car, my in-laws didn't drive their SL550 for months, and after they dropped by to see me, they couldn't get into the car with the keyless, had to use the little key. Once inside, luckily, the car started. Apparently, the car has 2 batteries, one for just starting the engine and the other for the electrical system (which was drained).

Not sure if the W204s have 2 batteries. There might be a short somewhere or perhaps a cabin light was left on?

nyca

How did they get the car to the dealer?

You'll know fairly soon whether the battery can still hold a charge.

Derspeed

Mine sometimes sits for a month without being started. It fires up every time.

RLE

You are certain that the key was not left in the ignition but in the off position? That will kill the battery overnight.

The early W211's had an electronic problem that would deplete the battery overnight but that one was solved long ago.

C300Sport

Although we do have lots of devices to draw juice, none of them should draw down a battery within a week or month. Sounds simply like a bad battery or some electronic device/function is failing to disengage as designed.

jrct9454

Like Derspeed, ours has often sat for well over two-three weeks with no problems.

Something is / was draining the system....too bad the dealer wasn't interested in finding out just what was the source.

Diesel Benz

The car would not turn lights off automatically. The point is that lights may be left on because of the car being parked on the road to an unsafe place. The parking lights need to stay on as long as there is any juice in the battery.

PS. only one battery on the W204.

smikes19

We jumped it. I left the jumper cables hooked up for at least 10 mins before the car would even attempt to turn over. Otherwise, the electronics would work, but if I tried to start it, all I would get is the instrument panel shutting off and then on again.

Yeah, they only have one key, and they arm the car whenever its in the garage.

Sorry, I meant the interior lights turn off automatically for my C350. They leave their exterior lights on the A position.


They do hear a constant ticking sound after they shut the car off. Not the typical metal expanding/contracting ticking, but more like a solenoid or something. I'll probably head to the dealer with them next time this happens...

joshg1001

on a related matter, one time, i walked into my garage after driving my lexus RX the previous night, and i could also hear like a ticking noise, like a bomb.

the battery was dead. so im guessing something similar here

Bokx_350

FYI I left my car sitting for over 90 days (from May till August) without any special precaution and the car opened fine with the remote and started without a problem when I got back.

RLE

He lives in California. They hardly dare to park on the street at night, let alone leave the lights on.

There is a fault. If your "dealer" can't get interested then direct them to make an appointment with the area MB Rep for you.

Mavrogenis

Our 10 month old C300 sat for 4 days and the battery was dead, registered 2.6 VDC on a meter. It has keyless go and all available options. After recharging the battery with a drive, the voltage was 12.9 VDC. I checked it after 10 hrs and the voltage was down to 11.9 VDC. I pulled out the keyless go button and am now using the key in the ignition switch. When I enter the car for the first time in the morning, the speedometer display turns on as soon as the door is opened with a message to not forget to take my key. This is not normal. Any idea what may have failed? Possibly the SAM?

Diesel Benz

My point was not that the car consumes power if left on the street with parking lights on but the fact that lights may be left on, even if the car was in a garage.

But it would be accidental to have lights on when they would turn off in the normal position.

Mavrogenis, if the power drain isn't from a near by KG key, I think you should first monitor the real power drain from the battery when the car is supposed to be in full sleep. If it has significant drain, pull fuses until you find the current reducing to normal level.