In this guide, we show you how to replace the battery in the engine bay on S and CL-Class vehicles from 2006-2013. It is important to point out that for model years 2007 and 2008, the battery is a smaller battery (Group Size V4) used only for starting the engine. For those model years, the larger Group Size 49 battery is located behind the rear seat. Starting with the model year 2009 Mercedes-Benz moved the larger battery from behind the rear seat to the engine bay. It replaced the smaller started battery used in 2006-2008 models.
In 2009 and newer model the battery found in the engine bay is used to crank the engine plus supply power to the onboard electrical system. A secondary battery (Part Number N000000004039 12 Volt 1.2Ah) is located under the dashboard. This is known as the auxiliary battery and is primarily used for ensuring the vehicle can shift to Park even if the main battery fails.
What you will need:
The battery size is different for pre-2009 models.
- 2009-2013 CL/S Class
- 2006-2008 CL/S Class
- Group Size V4
- This battery is difficult to find. There not many parts stores that sell a Group V4 battery. Because the compartment is larger than the existing battery, we have been able to retrofit a Group Size 65 battery without a problem. Group size 65 battery are cheap, but if you want to install OEM battery, your best choice is to buy the battery from the dealer. OEM V4 battery part number: A 230 541 00 01
- Group Size V4
- 10mm and 13 sockets
- 3/8" Ratchet
- Battery Terminal Brush
- Park your Mercedes-Benz S-Class or CL-Class on a safe working environment set the parking brakes and remove the key from the ignition.
- Pull the hood release under the hood of your S Class.
- Open the hood and locate the battery on the passenger side of the engine bay.
- Disconnect the negative terminal first, by loosening the 10mm bolt. The bolt does not need to be removed.
- Disconnect the positive terminal next.
- Remove the 10mm nut and remove the top bracket.
- Remove the 13mm bolt on the side of the battery. Remove side bracket.
- Lift the old battery out and place the new Group Size 49 battery in place.
- Clean the battery terminal using a battery terminal brush.
- Install side and top bracket.
- Connect the positive battery terminal.
- Connect the negative battery last.
- Start your car and ensure all is working properly.
- Synchronize windows, sunroof and steering able sensors by moving these parts full up/down (left/right).