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Secondary Backup Battery Replacement Instructions

[vc_row css=”.vc_custom_1451303326367{margin: 0px !important;border-width: 0px !important;padding: 0px !important;}”][vc_column][vc_custom_heading text=”Introduction” google_fonts=”font_family:Open%20Sans%3A300%2C300italic%2Cregular%2Citalic%2C600%2C600italic%2C700%2C700italic%2C800%2C800italic|font_style:300%20light%20regular%3A300%3Anormal”][vc_separator color=”blue” css=”.vc_custom_1451592738033{margin-top: 0px !important;margin-right: 0px !important;margin-bottom: 0px !important;margin-left: 0px !important;border-top-width: 0px !important;border-right-width: 0px !important;border-bottom-width: 0px !important;border-left-width: 0px !important;padding-top: 0px !important;padding-right: 0px !important;padding-bottom: 0px !important;padding-left: 0px !important;}”][/vc_column][/vc_row][vc_row css=”.vc_custom_1451303339072{margin: 0px !important;border-width: 0px !important;padding: 0px !important;border-radius: 1px !important;}”][vc_column width=”1/2″][vc_column_text]Is your Mercedes-Benz developing electrical problems? Maybe you are getting a Visit Workshop Malfunction?  Don’t panic, this can be an easy repair. You can fix this problem in less than 20 min and spend under $100.  If your car has been starting fine but you keep on getting the red warning on your instrument cluster that shows you a symbol of the battery then your Auxiliary/secondary 12-volt battery may need to be replaced. Fortunately, changing the aux/secondary battery is easier than changing the oil on your Mercedes-Benz.[/vc_column_text][/vc_column][vc_column width=”1/2″][vc_column_text css=”.vc_custom_1451597648756{background-color: rgba(224,224,226,0.56) !important;*background-color: rgb(224,224,226) !important;border-radius: 2px !important;}”]
Make: Mercedes-Benz
Model: E C CLA SLK ML S Class
Years: 2003-Present
Difficulty: Easy
Cost $45-$90
Time: 20 Minutes
Frequency: Battery lasts  4-7 years
[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column][vc_custom_heading text=”Preparation” google_fonts=”font_family:Open%20Sans%3A300%2C300italic%2Cregular%2Citalic%2C600%2C600italic%2C700%2C700italic%2C800%2C800italic|font_style:300%20light%20regular%3A300%3Anormal”][vc_separator color=”blue”][vc_column_text]It is recommended that you disconnect the main battery before you start to change the auxiliary battery. The main battery is located in the trunk. Locate it and disconnect the negative terminal.[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column][vc_custom_heading text=”Parts & Tools Required” google_fonts=”font_family:Open%20Sans%3A300%2C300italic%2Cregular%2Citalic%2C600%2C600italic%2C700%2C700italic%2C800%2C800italic|font_style:300%20light%20regular%3A300%3Anormal”][vc_separator color=”blue”][vc_column_text]To complete this repair, a new auxiliary battery is required. Here are the requirements for the battery:

  • 12 Volt
  • 12Ah
  • 170 Ampere
  • Sealed
  • AGM Battery

You can go with the OEM Mercedes-Benz Auxiliary battery or you could go with a more cost-effective alternative that meets the specifications. Here are some batteries we found on Amazon. Some of them were designed for motorcycles but they also can function as auxiliary battery for your Mercedes-Benz. Links are provided below, if you click on any of them you will be taken to Amazon to read reviews and check prices. Most of these batteries were listed for under $100 at the time of this writing, some of them as low as $45.

Replacement Aux Battery for Mercedes-Benz

[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column][vc_custom_heading text=”Tools Required” google_fonts=”font_family:Open%20Sans%3A300%2C300italic%2Cregular%2Citalic%2C600%2C600italic%2C700%2C700italic%2C800%2C800italic|font_style:300%20light%20regular%3A300%3Anormal”][vc_separator color=”blue”][vc_column_text]To change the auxiliary battery you will need a 10 mm wrench.[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column][vc_custom_heading text=”DIY Instructions on How to replace auxiliary battery” google_fonts=”font_family:Open%20Sans%3A300%2C300italic%2Cregular%2Citalic%2C600%2C600italic%2C700%2C700italic%2C800%2C800italic|font_style:300%20light%20regular%3A300%3Anormal”][vc_separator color=”blue”][/vc_column][/vc_row][vc_row][vc_column][vc_custom_heading text=”Step 1 Pull hood release” font_container=”tag:h3|text_align:left” google_fonts=”font_family:Open%20Sans%3A300%2C300italic%2Cregular%2Citalic%2C600%2C600italic%2C700%2C700italic%2C800%2C800italic|font_style:600%20bold%20regular%3A600%3Anormal” css=”.vc_custom_1451317663161{margin-top: 0px !important;border-top-width: 0px !important;padding-top: 0px !important;padding-left: 10px !important;}”][vc_column_text css=”.vc_custom_1451410742170{margin-right: 30px !important;padding-left: 10px !important;}”]Before you start, make sure you have your emergency brakes set. The next step is to pull on the hood release found under the dash on the driver’s side.[/vc_column_text][vc_single_image image=”3069″ img_size=”large”][/vc_column][/vc_row][vc_row][vc_column][vc_custom_heading text=”STEP 2 Open Hood” font_container=”tag:h3|text_align:left” google_fonts=”font_family:Open%20Sans%3A300%2C300italic%2Cregular%2Citalic%2C600%2C600italic%2C700%2C700italic%2C800%2C800italic|font_style:600%20bold%20regular%3A600%3Anormal”][vc_separator color=”blue”][/vc_column][/vc_row][vc_row][vc_column width=”2/3″][vc_column_text]Open the hood by pulling on the hood release located by the front grill. [/vc_column_text][/vc_column][vc_column width=”1/3″][vc_single_image image=”3070″ alignment=”right” onclick=”img_link_large”][/vc_column][/vc_row][vc_row][vc_column][vc_video link=”https://vimeo.com/150266843″][/vc_column][/vc_row][vc_row][vc_column][vc_custom_heading text=”STEP 3 Remove cabin air filter housing ” font_container=”tag:h3|text_align:left” google_fonts=”font_family:Open%20Sans%3A300%2C300italic%2Cregular%2Citalic%2C600%2C600italic%2C700%2C700italic%2C800%2C800italic|font_style:600%20bold%20regular%3A600%3Anormal”][vc_separator color=”blue”][/vc_column][/vc_row][vc_row][vc_column width=”2/3″][vc_column_text]The auxiliary battery is located under the cabin air filter housing. Locate the cabin air filter housing on the left of the engine bay. Remove the plastic bolt that holds the cabin air filter in place, then lift up the cabin air filter housing to access the auxiliary battery.[/vc_column_text][/vc_column][vc_column width=”1/3″][vc_single_image image=”3086″ alignment=”right” onclick=”img_link_large”][/vc_column][/vc_row][vc_row][vc_column][vc_video link=”https://vimeo.com/150268459″][/vc_column][/vc_row][vc_row][vc_column][vc_custom_heading text=”STEP 4 Disconnect battery terminals” font_container=”tag:h3|text_align:left” google_fonts=”font_family:Open%20Sans%3A300%2C300italic%2Cregular%2Citalic%2C600%2C600italic%2C700%2C700italic%2C800%2C800italic|font_style:600%20bold%20regular%3A600%3Anormal”][vc_separator color=”blue”][vc_column_text]FIRST, remove the NEGATIVE battery terminal using a 10 mm socket. Then remove the POSITIVE battery terminal. [/vc_column_text][vc_single_image image=”3101″ img_size=”large”][/vc_column][/vc_row][vc_row][vc_column][vc_custom_heading text=”STEP 5 Remove battery bracket” font_container=”tag:h3|text_align:left” google_fonts=”font_family:Open%20Sans%3A300%2C300italic%2Cregular%2Citalic%2C600%2C600italic%2C700%2C700italic%2C800%2C800italic|font_style:600%20bold%20regular%3A600%3Anormal”][vc_separator color=”blue”][vc_column_text]Remove the battery bracket using a 10 mm wrench.
[/vc_column_text][vc_single_image image=”3102″ img_size=”full” alignment=”center” onclick=”img_link_large”][/vc_column][/vc_row][vc_row][vc_column][vc_video link=”https://vimeo.com/150268461″][/vc_column][/vc_row][vc_row][vc_column][vc_custom_heading text=”STEP 6 Remove old battery” font_container=”tag:h3|text_align:left” google_fonts=”font_family:Open%20Sans%3A300%2C300italic%2Cregular%2Citalic%2C600%2C600italic%2C700%2C700italic%2C800%2C800italic|font_style:600%20bold%20regular%3A600%3Anormal”][vc_separator color=”blue”][vc_column_text]Lift up the old battery and install the new battery.
[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column][vc_video link=”https://vimeo.com/150268460″][/vc_column][/vc_row][vc_row][vc_column][vc_custom_heading text=”STEP 7 Install new battery” font_container=”tag:h3|text_align:left” google_fonts=”font_family:Open%20Sans%3A300%2C300italic%2Cregular%2Citalic%2C600%2C600italic%2C700%2C700italic%2C800%2C800italic|font_style:600%20bold%20regular%3A600%3Anormal”][vc_separator color=”blue”][vc_column_text]Once you place the new battery in place fasten the bracket first. Then connect the POSITIVE battery terminal. Connect the NEGATIVE terminal last. Make sure to place back the cabin air filter housing that goes over the auxiliary battery.
[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column][vc_video link=”https://vimeo.com/150268462″][/vc_column][/vc_row][vc_row][vc_column][vc_message message_box_color=”success”]You are done. Congratulations![/vc_message][/vc_column][/vc_row][vc_row][vc_column][vc_custom_heading text=”Recommended Parts ” google_fonts=”font_family:Open%20Sans%3A300%2C300italic%2Cregular%2Citalic%2C600%2C600italic%2C700%2C700italic%2C800%2C800italic|font_style:300%20light%20regular%3A300%3Anormal”][vc_separator color=”blue”][vc_column_text]
[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column][vc_custom_heading text=”VIDEO Related How To Repair Videos” google_fonts=”font_family:Open%20Sans%3A300%2C300italic%2Cregular%2Citalic%2C600%2C600italic%2C700%2C700italic%2C800%2C800italic|font_style:300%20light%20regular%3A300%3Anormal”][vc_separator color=”juicy_pink”][vc_video link=”https://www.youtube.com/watch?v=QR-E7_uSRB4″][vc_video link=”https://www.youtube.com/watch?v=6l20UMf3oT8″][/vc_column][/vc_row][vc_row][vc_column][vc_custom_heading text=”Related Articles” google_fonts=”font_family:Open%20Sans%3A300%2C300italic%2Cregular%2Citalic%2C600%2C600italic%2C700%2C700italic%2C800%2C800italic|font_style:300%20light%20regular%3A300%3Anormal”][vc_separator color=”juicy_pink”][vc_column_text]Here is a list of related how-to articles.

[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column][vc_custom_heading text=”Frequently Asked Questions” google_fonts=”font_family:Open%20Sans%3A300%2C300italic%2Cregular%2Citalic%2C600%2C600italic%2C700%2C700italic%2C800%2C800italic|font_style:300%20light%20regular%3A300%3Anormal”][vc_separator color=”blue”][vc_toggle title=”How many batteries does my Mercedes-Benz have? ” el_id=”1451301170585-ea30c4ad-10c3″]Many Mercedes-Benz cars starting from 2003 have two batteries. Typically there is the main battery in trunk and the auxiliary battery is found in the engine bay. Not all models have two batteries though.[/vc_toggle][vc_toggle title=”What is the reason to have two batteries on my Mercedes-Benz? ” el_id=”1451593075705-cb0b7f2c-e4c4″]The main battery which is typically found in the trunk is a full-size battery which supplies electricity to the on-board electrical system under normal operation.

The additional battery  which is often times called auxiliary battery or secondary is a smaller size battery which is used as a backup power supply in case the main battery is failing.[/vc_toggle][vc_toggle title=”What is the function of the auxiliary battery?” el_id=”1451593651524-973af1dc-3e22″]The additional battery  is used as a backup power supply in case the main battery is failing. You can learn more about the secondary battery here. [/vc_toggle][vc_toggle title=”Which Mercedes-Benz model have a secondary / auxiliary battery? ” el_id=”1451594155729-57d8d0b3-b714″]2012 – 2014  C250
2008 -2014 C300
2008 – 2014  C350
2008 – 2013 C63 AMG
2014 – 2014 CLA250
2014 – 2014 CLA45 AMG
2006 – 2006 CLS500
2006 – 2006 CLS55 AMG
2007 – 2010 CLS550
2012 – 2013 CLS550
2007 – 2013 CLS63 AMG
2004 – 2009 E320
2003 – 2003 E320 Base Sedan
2006 – 2013 E350
2003 – 2006 E500
2003 – 2006 E55 AMG
2007 – 2011 E550
2012 – 2013 E550 Base
2007 – 2011 E63 AMG
2013 – 2014 GLK250
2010 – 2014 GLK350
2013 – 2013 SL550
2013 – 2013 SL63
2012 – 2013 SLK250
2012 – 2013 SLK350
2012 – 2013 SLK55 AMG
[/vc_toggle][vc_toggle title=”Can I drive my car with a failed auxiliary battery? ” el_id=”1451595870956-91ec63a1-fd53″]Even if the auxiliary battery may have failed you may notice that your car starts and runs fine. You can typically drive the car if you stuck away from home. We don’t advice that you continue to drive the car with a failed auxiliary battery.

It is a concern if the main battery fails. Several Mercedes-Benz models use SBC (Sensotronic Braking System) brakes or brake by wire. In that case you may experience reduced braking power or no brakes.[/vc_toggle][vc_toggle title=”Why does the red battery light displays on dash when I first start the car?” el_id=”1451596620532-22646111-64c4″]TBenz_auxiliary_secondary_battery_replacement_How_to_DIY_05hat’s because the car has detected that the auxiliary or the primary battery in trunk have low voltage. You could either have a system that drains your battery when the car is parked or one of the batteries is failing. If the car starts fine, there is no hesitation on starting, we would recommend replacing the auxiliary battery. If you still have the red light, then the primary battery may be the problem or electricity drain overnight.

[/vc_toggle][/vc_column][/vc_row][vc_row][vc_column][vc_custom_heading text=”Applicable Part Number” google_fonts=”font_family:Open%20Sans%3A300%2C300italic%2Cregular%2Citalic%2C600%2C600italic%2C700%2C700italic%2C800%2C800italic|font_style:300%20light%20regular%3A300%3Anormal”][vc_separator color=”blue”][vc_column_text]Mercedes-Benz Secondary Backup Auxiliary Battery

  • Genuine Original 2115410001
  • Manufacturer Part Number:  2115410001
  • Interchange Part Number: A 2115410001
  • MB211-541-00-01

GENUINE MERCEDES Auxiliary Battery Relay

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4 comments

  1. This is NOT instructions for the CLA250 Aux Battery. 1) the battery is in the engine compartment, not the trunk as stated and 2) the cabin air filter is NOT on the left side of the engine compartment. I’ve yet to find where my aux battery so I can replace it.

  2. I had the Battery Malfunction problem on my Mercedes-Benz and replaced the auxiliary battery following this guide.

    Error message gone. Thank you!

    • Hi fanatic. Just bought 2013 MB from auctions. Message on dashboard says Auxilliary battery malfunction’ Is this the same message you had. Also how much was the new battery?
      Thank you
      Grumpy1962

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