12 volt battery replacement
Thread Starter
Member
Joined: Nov 2011
Posts: 104
Likes: 2
From: Florida
2019 CLS450 4 Matic 2011 E550
12 volt battery replacement
Does anyone have a diagram to replace the battery inches trunk? I want to see how to take apart the interior. I have some strange things going on. When I get into the to start it after sitting in the garage overnight my dash design settings change from sport to classic. The car still has the original 12v battery. Yes I know shocking 6 years old. Next does it need to be coded to the car? Thanks for any help.
Member
Joined: Feb 2010
Posts: 77
Likes: 18
From: Portland, OR
2024 GLE450 & 2022 CLS450
Didn't see anything online about removing the panels to get to the 12v battery. If a replacement battery is needed, again, didn't see anything online about coding the battery to the car. Even looked at the owners manual, which was silent on the issue of battery coding. Of course, the owners manual recommends having the dealer replace the battery.
Have you by chance tried charging the battery with a "smart" charger such as a CTEK? Some of the CTEK chargers also have a battery "reconditioning" feature. According to CTEK, this is "a special reconditioning function that restores stratified and deeply discharged batteries."
Lastly, is there a battery warning message or error message appearing in the dash? If so, what does it say?
Have you by chance tried charging the battery with a "smart" charger such as a CTEK? Some of the CTEK chargers also have a battery "reconditioning" feature. According to CTEK, this is "a special reconditioning function that restores stratified and deeply discharged batteries."
Lastly, is there a battery warning message or error message appearing in the dash? If so, what does it say?
Thread Starter
Member
Joined: Nov 2011
Posts: 104
Likes: 2
From: Florida
2019 CLS450 4 Matic 2011 E550
I have tried charging the battery with a some what smart charger. It does charge. It will charge after 20-30 minute trip. There are no error messages on the dash. It's just strange after 1 or 2 days in the garage my display goes back to comfort instead of sport. Plus the heads up shuts off. I had the battery load tested from under the hood. It came back 775 amps. They felt it wasn't enough to condemn the battery. I know these cars can be sensitive to low voltage. I would pr3fer not spend 4 - 500 for the battery unless needed. If I knew how to dismantle the trunk interior I would just buy a
Member
Joined: Feb 2007
Posts: 160
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From: Sandy Springs, GA
'15 E350, '20 S560
There are several videos on YouTube showing how to change both batteries. Major caveat, make sure to provide power to the car when changing the starter battery and register it with the system to insure a proper charging rate after it’s installed. As far as I know, it’s not necessary to register the auxiliary battery. Don’t know how to register? Well, you’ll need to have a diagnostic tablet like iCar Soft or have a shop with the proper equipment to do it for you. Typical cost is from $50 to $150.
Newbie
Joined: Aug 2025
Posts: 5
Likes: 3
2020 CLS450
Did you ever find any instructions for removing trim in trunk to get to the battery in your CLS450? I have a 2019 CLS450 and want to replace battery. Removing trim is trunk is not described in users manual and not finding anything good online; e.g. Youtube or anywhere. Local MBZ dealer won't take me in until a week from tomorrow. I'd replace it myself, but don't want to break any trim pieces or fasteners by working blind.
Newbie
Joined: Aug 2025
Posts: 5
Likes: 3
2020 CLS450
Did you ever find any instructions for removing trim in trunk to get to the battery in your CLS450? I have a 2019 CLS450 and want to replace battery. Removing trim is trunk is not described in users manual and not finding anything good online; e.g. Youtube or anywhere. Local MBZ dealer won't take me in until a week from tomorrow. I'd replace it myself, but don't want to break any trim pieces or fasteners by working blind.
https://www.pelicanparts.com/techart...im_Removal.htm
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