2007 C230 Auxiliary Battery Location
 

Need some guidance from the vast knowledge here. I'm trying to locate the auxiliary battery in my 2007 C230 Sport. Tried looking in the owners manual that I download but didn't have much luck there. Any one know where it's located in the vehicle? Much appreciated!

Other members will likely confirm, but I do not believe that the W203s have an aux battery.

Thank you for the reply. The reason I think there is another battery is because I've changed the main battery twice and each time the alarm goes off when the battery is removed. Plus now with a new battery I'm getting the red battery indicator on the cluster. Might need to take it to the shop I use but I thought it was simple to find possibly.

It's a bit odd because some people seem to give a definitive answer saying that there is no aux battery, but others have suggested checking here:

Look under the hood of the car on the passenger side under the cover.The cover is held on by a 10mm plastic nut. Once removed you can gently pull on the tabs on the left and right side while lifting up on the cover.