Learn how to install a new auxiliary battery in a Mercedes-Benz E320. We’ll show you how to replace/change/remove with simple tips and tricks to help get you started!
Tool List: 13mm wrench, 10mm wrench, Torque Wrench
Some vehicles like this Mercedes-Benz E320 have two batteries. They have the regular 12 volt starting battery and an auxiliary or a small additional battery that is usually used to keep the vehicle’s electrical system voltage from dropping too low during periods like start/stop when the engine starts. This is particularly useful to keep thinks like GPS’s and computers from resetting. This Mercedes has it’s little auxiliary battery located under the hood, under a little cowling. The main 12 volt starting battery is back in the trunk. To replace this small auxiliary battery, which will go bad after awhile, is a fairly straightforward procedure. Although this video may provide you with the basic procedures, we recommend that you check with the vehicle manufacture’s step by step procedures found in service/repair manuals for the vehicle you are working on.
The use of a memory saving procedure will keep the vehicle’s computers memory’s alive during the battery replacement procedure. Referring to our Memory Saving video will provide you with various memory saving procedures that can be used according to vehicle manufacturer’s requirements. https://youtu.be/vSP3ShcaFgQ
Some late model vehicles must have the 12 volt battery registered with the vehicle’s Battery Control Module or Computer after replacement. See these videos on Battery registration and coding for more details on the procedures at https://youtu.be/TGKohKZHzr0 & https://youtu.be/cxOK_DczRGg
Always wear safety glasses and gloves when working with or near batteries.
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very easy to follow thank you !
Great site. Very useful
My battery had dead, do I have to change for the original battery at Mesades or I can also use other brand batteries that they sell at other shops?
Puedo conectar directo una batería de 12v 7Ah para q no se apague el radio , al momento de prender el carro
Could the aux battery cause the car to not start? or the main battery? I have a 2005 e320 but my ignition switch would turn because it won’t read the key. Could the battery be the problem, EIS, or a new key?? By the way everything internally still works. Radio, lock buttons.
Can anyone tell me the cost of replacing the aux. battery? I live in VA. Being a female and driving an import car can make some mechanics see only the dollar sign, that's been my experience over the years, so I need to be informed.
Great video!
If this battery goes bad, would it cause brake failure??
Our fedex sprinter is very sluggish . Has all the assists inop. And says auxiliary battery malfunction . They can't figure out what's wrong with it . Any ideas? Feels like the turbo is off
Hello I need to know what kind of battery for aux so I can buy new one
The AUX battery is about as BIG as my Vauxhall Astra Battery TOTAL!
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I was told that ALL Merc Bolt Heads were TORX Fit?
Does the W211 E420 CDI 2008 have an auxiliary battery ?? Thanks
Hey Thank for this Video, were is the aux battery located on E63 2013/2014
Help me out I have a e320 the back battery is good and my alternator is good but my car doesn’t start can it be this little battery that is bad I haven’t checked it yet
Hi, where’s that small battery on S350 2011 model please? Is there one ? Thank you
Hi good video – were is the aux battery located on – 280 E class 2017 auxilliarly battery – regards
The auxiliary battery is used primarily to support the computerized braking system.
I have a 2014 GLK 350. Should I use a memory saver when replacing the auxiliary battery?
Strange – you did not even mention what Mercedes model you talking about. Different models have a different compartment for auxiliary battery. And some ot them don’t have an auxiliary battery at all.
Should I recharge the auxiliary battery before replacing it
Nice simple video that doesn't over-complicate this. Confidence in this guy who is ASE certified and does it right. A different video shows a guy taking the red terminal off first and reconnecting it last. Wrong. Again, nice job on this one.
Could you tell me where is the Aux Battery for 2015 Mercedes S550 non AMG located? Thank you
Look like you replace the main battery, not the auxiliary battery.
What is the auxiliary battery used for and when do you know when it needs to be replaced? Wouldn’t the main battery be good enough for the electrical systems as well? Either ways you will connect a back up battery (in parallel) before you change the main battery but is the same (parallel connection needed) to change the auxiliary battery as well?