W212 Auxiliary Battery Interval

Aston Dabb

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W212 AMG 2010 E350 CDI
Hello all,

I am replacing the main battery on my 2010 E350 CDI at the weekend for a new AGM battery due to a high idle fault (put on the main battery being faulty) but I was wondering whether I should replace auxiliary battery at the same time? There aren’t any faults on the dash saying aux battery is defective, however I’m not sure how long they last. Any advice?
 

malcolm E53 AMG

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I wouldn’t worry about the auxiliary battery until you get the fault indication on the dash
 

sonic

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E350CDI, SLC250d, FJR 1300
Hello all,

I am replacing the main battery on my 2010 E350 CDI at the weekend for a new AGM battery due to a high idle fault (put on the main battery being faulty) but I was wondering whether I should replace auxiliary battery at the same time? There aren’t any faults on the dash saying aux battery is defective, however I’m not sure how long they last. Any advice?
Are you sure you have one? I have a 2011 212 E350CDI & it docent have one.
 
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Aston Dabb

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W212 AMG 2010 E350 CDI
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Are you sure you have one? I have a 2011 212 E350CDI & it docent have one.
Yes the W212’s have an aux battery behind the glove box it’s not a proper aux battery like they have on the W211’s; it’s just a 12v 1.2ah battery behind the glovebox, small and rectangle
 
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Aston Dabb

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I wouldn’t worry about the auxiliary battery until you get the fault indication on the dash
Should I remove it and charge it? I have bought myself a smart battery charger and have purchased a new MB AGM battery for the merc today
 

Blobcat

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Should I remove it and charge it? I have bought myself a smart battery charger and have purchased a new MB AGM battery for the merc today
No, just charge the big juan
 

John Laidlaw

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Aux on my 2014 212 was in the boot
 

maniyarn

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w212 2011 e350 cdi avantguarde
Thanks for the video link Malcom210. Helped when I got the auxiliary battery warning on my 2011 w212 e350cdi with no stop start.
It has the N000000004039 battery in the dash on the driver side.
I decided against going down the genuine MB route and went for the yuasa lab1.2a link below. only ~ £10 from toolstation vs the ~ £70 MB one.
I had the additional issue that the previous owner had installed an extra speaker directly behind the air vent screwed into the side plastic bracket so space was even more of a premium. if you do go down this yuasa route be aware that unlike the original, this one has both f1 connectors so you'll need a f1 to f2 adapter. In the end I got the adaptor from a local motor spares shop for 30p, having had no luck in halfords, toolstation, wickes, screwfix and various local electrical stores. They are available via ebay for £1 with a £6 delivery charge...

https://www.toolstation.com/sealed-lead-acid-battery/p29879
 
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