Irfie

This is for the future w204 owners -

How to see or spot a battery issue?

-Car will have A/C blower issue
-Command system will turn off and turn on when you switch the car on
-When locking the car, the lock horn will be slightly less
-Car will have issues with starting up

How to know it is not an alternator

-If your car is all ok when the car is running
-Command system is stable when the car is running


What to do about it?
-Change your battery
-The batter comes in 2 Amps (88AMH and 100AMH) Both are okay but its better to go with 100AMH
-Total Cost for battery from USD 60-100

Thank you and enjoy your car.

Make sure to change the battery every 1-2 years so that cars all electric system is good. (The battery would last depending on the condition its kept, heat, etc will destroy)

michail71

Another clue about the battery is the brake hold will not engage. My original battery had to be replaced just short of 4 years but was fully covered under the warranty.

superangrypenguin

Interesting thread, and quoted is a very interesting comment to me.

I presume you're referring to the car applying the brakes after you've depressed it in a hard manner?

If so, I wonder why this is, and if this is the case, it goes to show how **** MB engineers have designed the system logic in these cars.

Why? Because an alternator would have to fail and the battery would also have to fail before this becomes potentially disastrous.

I see designs like this all the time on planes when they design their systems and reliability, last I checked to 3 nines or 5 nines (inputting a fact that every life has a $ figure, but that's besides the point), but I have not seen this on cars.

Kudos to MB if this is true!

michail71

Yes, they engineered impressive safety in this system. I was impressed by it as well. I wish they'd put up a service message about the battery though. I had no other battery symptoms.

Jeep's incident in the death of Anton Yelchin and others is an example of how important these things are.

I test drove a BMW the other day that failed to brake hold. It just kept slowly slipping forward. It made me appreciate the little things on a Benz you might not always notice.

I was driving my loaner w205 yesterday and opened the door while at a slow roll. Much to my surprise the car braked and went into park. Although I guess one could jump out the window, lol.

superangrypenguin

Cool, thanks for the info. I LOLed really hard at your last comment

The Germans are weird though. They don't have a batt warning message as you put it but they'll go to all ends of the Earth to try and prevent an issue that may very well never come to be.

Reminds me of the Russians using a pencil in space vs the Americans overengineering stuff

Demvang

Another indication is ... cranking with dashboard lights on, then they blink or turn off and on.

NZ-Merc

Another one is sun roof loosing its memory to its stop full open and full closed positions so all it will do when opening and closing is stop start and stop continually like it is stuttering.

davis449

I was experiencing all kinds of these symptoms. Every time I hit the brakes, the headlights, interior lights, etc. all flickered. Power seating functions slow to move, the windows slow to roll up and down, and the car was slow to fire up when cranking. I even had a cylinder shut down on me toward the end of a 6 hour road trip. Not the battery...bad ground. Took three visits to the dealer for them to actually troubleshoot the issue instead of throwing parts at the problem.