GOT AN AUXILIARY BATTERY?
 

Well I didn't know I had one until the Economy feature started messing up,,that feature that shuts off the engine at a stop light when the car is warmed up.It also has something to do with the brake hold feature,because that started acting up too,...Car has 36K miles... And my CPO warranty doesn't cover it,,they consider it like a light bulb or some wear and tear item.Dealer said they started using them in 2014,,so beware.
Long story short,,they fixed it free,a 500$ part,plus labor,,holy crap.

i changed the auxiliary battery in a 2010 E350 behind the dashboard it cost me an overpriced $75 for the part but i changed it myself easily. glad they fixed it for free but theres lots of DIY on it in the forums

my 2010 e550 cost me $25 bucks, a piece of electrical tape and 2 hours. $500 this is theft.

Guys,,was it the size of a motorcycle battery?

Started after 2012 I believe using the larger battery in the trunk. The part should be no more than about $150 at a dealer, but yes they are not covered once out of bumper to bumper warranty, as batteries are a maintenance item. Same with the main battery.

This is super common though, there are literally dozens of posts about them failing and replacement. Not something new.

OK,,didn't know about the common issue,,my 4th Benz and never had to deal with it,,,also explains why my trunk was all messed up when I got the car back.,,thanks for the info.

Mine started failing when the car was left outside for a couple hours in -35c weather, but was fine during the day or left in garage. Mine lasted 8 years. Battery was about the size a normal 355ml can.

Isn't that the main battery? In depending what year, its either up front beside the engine or in the trunk beside the spare tire. There's a secondary battery located below the instrument cluster in the driver seat. The secondary battery would be the auxiliary and powers secondary features such as blind spot assist and brake hold.

Edit: I was partially correct, depending on year auxiliary battery can be a bigger size in the rear.

Your early car has the tiny dash battery, the later ones have a larger battery in the trunk and no more battery in the dash.

Wtg Key,,that's the aux,,like I said,,like a mcy battery,,and same size as my grandson electric jeep.����.Thanks again to all.
BTW, where did they put the main batt,,under the seat?I haven't really looked around cause its been fine otherwise.

Awesome,,tx again.

36k miles and CPO does not cover it. You should be under factory warranty unless you timed out on years. What year is your car?

Yes I get that now,,its a 14 with 36k miles.Basically the dealer felt ashamed that they sold me a CPO car with a weak ass Aux battery. So they did a good will repair, realizing I'm a loyal customer. Its supposed to be like new when u buy one of these cars,,they stepped up.

CPO warranty covered mine TWICE in 1 year....

How did u kill that battery twice?

I figure the first one was a dud from sitting on dealer lot for year and not being driven before I bought car as CPO.

Second I figure was just bad battery or something unlucky as another dealer checked everything out in another state as I was traveling 1000 miles from home.

All I know is when they go out you lose all the cool features of the car and for me losing Distronic w/steering assist+ SUCKS as that is my favorite feature.

does the aux batt. malfunction causes adaptive headlights to not work?

I do not remember on headlights

HOLD does not work; that I remember - another I like.
I wonder if those special BRAKING ones do not work?

Neither Dealer could explain 2 batteries failing within 9 months.
I did ask is it properly charging and they both stated yes.... so I write it off to bad batteries...

If it happens again though my volume will go up.

yeah, distronic plus features, lane departure warning and HOLD feature won't work. Today I got Adaptive Highbeam doesn't work error message.

Highly possible this is related to the accident.

on the other hand, I'm skeptical I may need to replace my Aux battery.
https://www.eeuroparts.com/Parts/740...ry-SBC-S6590B/
or
https://www.fcpeuro.com/products/mer...hoCLNYQAvD_BwE

1. Is this the correct part?
2. This website provides lifetime warranty, just called them, and the lady on the phone said,
eEuroparts.com:
"if the battery doesn't hold the charge down the road 3 or 4 years after, order a new one and we will refund you once we receive your old/non-working one. "

and

"Bosch doesn't provide lifetime, but the warranty would go through us, no extra cost."


Does it seem legit? Mercedes dealer asked 150$ probably including installation, with 2 year warranty.
Which route to take?

Just dropped off my vehicle for hard 3rd gear shifting (the one that happened at 47k Miles) and they sent me with a loaner vehicle until that.

Wow lifetime warranty but would ti cover the replacement as well?
Batteries do not last forever.
Price is higher then say a local auto parts store but life time free replacements?
Heck once you get the second one for free it has paid for itself..

Question is how long will they be in business?

That is a million dollar question.

On the other hand FCPEuroparts offers the same, free shipping, 2$ more than the eEURO.

Now, where did you find it for cheaper?

million dollar question.

On the other hand FCPEuroparts offers the same, free shipping, 2$ more than the eEURO.

Now, where did you find it for cheaper?
Like this? I didn't even check the part number yet. This is aftermarket not OEM(MB) or Bosch.
https://www.ebay.com/itm/Mercedes-W164-W251-GL-ML-R-Class-NEW-GENUINE-Auxiliary-Battery-1-2AH/112041275311?fits=Year%3A2014%7CModel%3AE350&epid= 1237141746&hash=item1a162e2faf:g:NxsAAOSwQTVWA4K1: sc:ShippingMethodExpress!28262!US!-1:rk:3:pf:1&frcectupt=true

Cheaper:
Local Auto Zone = $99 3yr
https://www.autozone.com/ignition-tu...4_994522_25698

Some may not have in stock but can get in day.
Napa was $104
Adavanced was $110

Good Luck

gotcha, I believe they would install too, if I buy it from them.
On the other hand, there is a 20$ off of 100 or more. That should bring close to $100 for the battery.

Thanks for the info.

1. Autozone or similar for 3 year warranty.
2. Those euro websites which we don't know how long they will stay in business for Lifetime warranty.

3. Which I won't take anyway is Mercedes Dealer 142.38+ taxes for 2 year warranty. Since this is not the main battery, I'm leaning towards the cheaper option.

I think it covers it forever so some people have bought the oil change kit and keep sending in the old oil for a new oil kit. You have to buy a new one and then send in the old one before you get reimbursed so you have to pay shipping to return it.

They're a little bit more than some places, but if you think the part might fail at some point, it's worth it for the lifetime warranty. But some parts like alternators already come with lifetime warranties from an auto parts store and they're cheaper and local so it's not always worth it.