M-Class (W166) Produced 2012-2015

ML400 batter(ies) replacement

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Old Oct 16, 2017 | 03:08 PM
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2012 ML350
ML400 batter(ies) replacement

How do you replace both the starter motor battery (under passenger seat) and the auxilary battery under/side cargo panel?

For the life of me, I can see how to 'easily'get at these batteries for replacement. Looks like the passenger seat and floorboard have to be removed for the main battery and the back cargo/spare tire floor board has to be removed as well.

Any information greatly appreciated!

(also - are both batteries AGM type? or plain SLA? thanks again)
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Old Oct 16, 2017 | 09:57 PM
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2018 GLC 4MATIC
Here are some vids how to do this work.
I note them for myself when Im ready.


Aux located behind the right side rear panel in the cargo compartment (below the spare near the tail light)
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Old Nov 12, 2022 | 01:35 PM
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2012 ML350
Time to replace the main engine battery (under passenger seat). Is there a recommended brand for long life? (Exide? Interstate?)
Thanks
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Old Nov 13, 2022 | 08:39 AM
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2013 ML550 US spec. Air+Offroad pkg
I got 9 years out of my OE batteries, and found getting OE from dealer was less than $10 more for each, so went with OE again. Main battery is Bosch (branded MB), and not sure who makes Aux. Also noted aftermarket main batteries didnt have the breathe nipple on them for gas venting. Check your local online price (usually 15-20% cheaper if you search online from your dealer thru MB than walkup counter). If you dont go OE, I have had best luck with Interstate batteries over the years with multiple cars. Make sure you get an AGM for main battery since it sits inside cabin (same as OE).
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Old Nov 13, 2022 | 09:52 AM
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Leetom - Thank you! This is what I needed to find out.
I am at 7 years now and thought I would change the battery just as a precaution. What did your battery do when it was end of life? Did it give you a warning (crank slow) or just die. It is the "just dying" part I want to avoid. I replaced the auxiliary battery (with OEM) a couple of years ago.
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Old Nov 13, 2022 | 10:06 AM
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2013 ML550 US spec. Air+Offroad pkg
Mine suddenly did the slow crank, and I replaced. Was thinking of replacing proactively at the time, so timing was good when it did the slow crank. Have read that letting them go too long can cause computer headaches, so best to replace at first signs...or before. Tip...move pass seat ALL OF THE WAY FORWARD to gain access. If you keep pressing seat button, seat will lift and tilt forward to help access. I think my Bosch (MB) battery was about $185 about 1.5 years ago purchased online from my local dealer (think walkup parts desk price was $225)
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