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.
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