Oily rag

Hi all,
Please forgive me if this thread has been done to death but trying to get a satisfactory answer to a simple question is doing my head in!
I have a 2010 W204 C180 Se Executive Blue Efficiency.
All I want to know is and I have never seen so many conflicting answers, whoever you ask, the procedure for replacing the battery.
The car is not stop/start and has no automatic mirrors, no heated seats etc etc.
Simples!..........(1)...I want to change the battery
(2)..Do I need to maintain 12v supply to maintain memory?
Or (3) Do I NOT need to maintain 12v supply?
It seems the simplest question in the world so why can nobody give a definitive answer?

If it's only a question of reprogramming the windows or radio presets, that's fine but I don't want to screw up any electrics or modules.
PLEASE can anyone give me a sensible and reliable answer.
Thank you, in anticipation.
Oily Rag.

ezshift5

I used the MB roadside assistance number (the dealer is only 8 miles away): a spiffy young man arrived.....replacing age 7 battery with little effort. Circa $211 February 2018.

Cheers,


ez

Oily rag

SEE WHAT I MEAN!!!!!
Hi Ez,
Thank you for your comments but it's still not the answer I want.
I want to replace the battery myself, I don't want anyone else doing it for me.
All I want to know is do I need to keep a 12v supply going while I am doing it.
As I said....Simples

ezshift5

Hi Oily Rag..................

I called our local dealer, He said once the voltage drops below a certain level you lose certain memory functions.

I reckon that would mean you need to have that 12v current flowing...............

Hope that will help you. (I had a Royal Navy instructor during my time in radar school - - - He had a lot of starch.......just like you.)

ez

Oily rag

Hi Ez,
Thank you.
Appreciate that...will keep the old 12V flowing while I'm changing batteries over.
Sorry, didn't mean to come across as starchy.

Thanks for your help.
Oily rag

RNajarian

I just replaced the battery on my 2012 C350 Blue Efficiency. I removed the battery, did not hook up any external power supply. Car was without power for 25 minutes, did not lose any memory.

That was my experience

BeaverMjr

Earlier this year, I replaced the right hand steering wheel controls due to them de-laminating. The first step is to disconnect the battery and to wait 25 minutes so that the air bag does not go off. when everything was done, I reconnected the battery and everything was fine.