Changing battery in Mercedes S-Class - HELP

[IceBoy]

Hi All,

I've just ordered a new battery for my W220 - S320 CDI (2005), as on frosty mornings the car is slow to turn over.

The battery is located in the boot and seems to be easily accessible but I'm worried some of the gazillion computers will throw a wobbly, if I just remove and replace.

Does anyone have any experience of changing batteries on these sorts of cars and/or what I should do?

Thanks in advance.
Iceboy

[Scrump]

Helped a friend replace his a few years ago. Nothing unusual as I recall.
When we finished there was a warning about the power steering and we had to move the wheel from lock to lock and then take it on a drive. The light went out on its own so no need for a trip to the dealer to get it reset.

Edit to add: I am now wondering if my mind is playing tricks on me and the power steering issue was not the S class. If it wasn’t then the S class went without any warnings!

Edited by Scrump on Wednesday 30th January 18:55

[AREA]

This may help: http://www.mercedesmedic.com/6980-2/

[anonymous-user]

That’s a great guide AREA. Good find. What I will add is that make sure everything is properly torque. I used a torque wrench when replacing a battery on a W205. There were different settings for the bracket and battery terminals. Consult WIS if you can.

[Watchman]

I have had both my main battery and the accessories battery out of my 2011 GL the past two weekends. The only issue upon reconnecting them was that the side window one-touch facility was lost. I had to hold the button all the way to top, and then when I let go they wound down again to about half way. Holding the button all the way up again allowed for them to stay all the way up.

To reinstate the one-touch facility you have to hold the button all the way up and then +15 seconds. I had to do this a couple of times but the facility worked then.

[AREA]

Super_G said:

That’s a great guide AREA. Good find. What I will add is that make sure everything is properly torque. I used a torque wrench when replacing a battery on a W205. There were different settings for the bracket and battery terminals. Consult WIS if you can.

WIS operation steps:
- Remove ignition key
- Pivot trunk cover up
- Unscrew screw and remove holder
- Connect quiescent current retention unit
- Disconnect ground lead from battery
- Remove gas vent line from battery
- Remove positive pole cover upward
- Disconnect positive lead from battery
- Remove battery
- Install in opposite order

If you wanted to avoid going through the window, steering reset procedure and, due to some strange oversight, happened to have mislaid your collection of 'quiescent current retention units' then a VERY carefully placed, insulated and suitable charger unit or jump pack could save the effort (I've done this on an SL once but since then just resorted to the 'manual recalibration procedure' as per the video link in prev post!)

Judging by how a couple of our cars have been returned from main dealer servicing (e.g. having to reset the windows and other systems myself) seems they don't bother with quiescent current retention.

[Watchman]

If you have an accessories battery, and you don't disconnect it, you might retain all your settings. Just a thought.

[ChrisHampshire]

I use one of these to preserve the 12v supply to the ECUs whilst disconnecting the battery:

https://www.amazon.co.uk/TONWON-Connector-Diagnost...

Works a treat, no resets needed.