Auxiliary Battery
Thread Starter
MBWorld Fanatic!
Joined: Nov 2009
Posts: 2,616
Likes: 160
From: Southeastern USA
2010 E350 Luxury Sedan, Engine 272 (V6)
Auxiliary Battery
My 2010 is 15 years old, but only has 50,000 miles on it. Mostly short trips around town and may go for days without driving it at all. Have never had a problem with auxiliary battery.
How long do they last? Can they be inspected/tested?
Plan to have independent European car repair facility do O&F change and a few inspections next month. All other services are up to date.
Incidentally, the repair place is now using Castrol Edge Euro Car full synthetic oil for all vehicles they service. Including my Toyota Tacoma. Is it really worth it?
Thanks,
How long do they last? Can they be inspected/tested?
Plan to have independent European car repair facility do O&F change and a few inspections next month. All other services are up to date.
Incidentally, the repair place is now using Castrol Edge Euro Car full synthetic oil for all vehicles they service. Including my Toyota Tacoma. Is it really worth it?
Thanks,
Out Of Control!!
Joined: Apr 2019
Posts: 11,922
Likes: 6,775
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
couple open questions
My 2010 is 15 years old, but only has 50,000 miles on it. Mostly short trips around town and may go for days without driving it at all. Have never had a problem with auxiliary battery.
How long do they last? Can they be inspected/tested?
Plan to have independent European car repair facility do O&F change and a few inspections next month.
All other services are up to date.
Incidentally, the repair place is now using Castrol Edge Euro Car full synthetic oil for all vehicles they service. Including my Toyota Tacoma. Is it really worth it?
Thanks,
How long do they last? Can they be inspected/tested?
Plan to have independent European car repair facility do O&F change and a few inspections next month.
All other services are up to date.
Incidentally, the repair place is now using Castrol Edge Euro Car full synthetic oil for all vehicles they service. Including my Toyota Tacoma. Is it really worth it?
Thanks,
-- yes it's internal resistance is still testing ok after every start cycle else a display error message would ask to replace it.
-- Is it nearly spent... yes most likely but can last as long as it doesn't need to work, it survives.
DO keep MAIN Batt trickle charged so AUX never drains low (RIP).
Q: "Castrol Edge Euro" Oil:
-- Everyone has a prefered oil "MB-Approved" listed or not.
Castrol/BP blends many fine approved lubricants.
Last edited by CaliBenzDriver; Oct 25, 2025 at 06:15 PM.
MBWorld Fanatic!
Joined: Dec 2011
Posts: 4,372
Likes: 945
W212 FL
I had to replace mine in 2023 and the model year is 2015 . The mileage was around 110K . I had not have it tested but ECO system was never engaging since I bought it and it was 1st thing to give me a hint about a weak AUX battery
That's an awesome record to me given the age of the battery and low mileage .
As for the oil, I would stick to what the manufacturer recommends .
Happy Driving
That's an awesome record to me given the age of the battery and low mileage .
As for the oil, I would stick to what the manufacturer recommends .
Happy Driving
Last edited by BenzV12; Oct 26, 2025 at 02:22 AM.
Thread Starter
MBWorld Fanatic!
Joined: Nov 2009
Posts: 2,616
Likes: 160
From: Southeastern USA
2010 E350 Luxury Sedan, Engine 272 (V6)
Update. After driving my car for about 30+ minutes, the Aux. Battery warning does not come on any more. Since I have been driving it more often, it has not come on again in last few months. I assume it is getting recharged? Indy wanted between $100-200 depending on which battery and would have to leave it for a couple of days to allow them time to determine battery type and order or get it.
As for oil, M-B and dealership recommend M-B oil. Dealership used to add an additive as well.
As for oil, M-B and dealership recommend M-B oil. Dealership used to add an additive as well.
Out Of Control!!
Joined: Apr 2019
Posts: 11,922
Likes: 6,775
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
The AUX is small battery. It really is a motorcycle battery size - It has NO CHARGING CURRENT LIMIT control...
That means AUX sees high current surges when it is low.
To prevent surges, don't let AUX get low by using CTEK float charger to maintain the main.
Simply aim to keeps AUX from being discharged.
That means AUX sees high current surges when it is low.
To prevent surges, don't let AUX get low by using CTEK float charger to maintain the main.
Simply aim to keeps AUX from being discharged.
MBWorld Fanatic!
Joined: May 2012
Posts: 2,359
Likes: 1,555
From: Pepper Pike Ohio
24 GLS580 '23 E450 4matic 12 E350 4Matic
Yes, As Cali says in a 2010 its a small battery in the dash behind the drivers side access panel, pry the cover off carefully with a plastic tool then it's only a bolt holding the battery bracket and two electric leads, Positive does have an inline fuse, but yours is obviously still OK.
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Junior Member
Joined: Nov 2024
Posts: 47
Likes: 28
GLK350, SL500 (R230), E55 (w210)
Low aux battery can prevent shifting from P to D, etc. Has happened to me (many months after it no longer activates stop/start)
Buying on Amazon and changing yourself, very easy and low cost
Buying on Amazon and changing yourself, very easy and low cost
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