Life of the original battery
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Joined: May 2003
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From: Long Island, New York
2018 E400 4matic Wagon
Life of the original battery
I have a 2018 E400 that is now 5+ years old with 32k miles. The car is used most days and there have been no warning signs about a low battery. The battery is the original AGM battery. Should I start thinking about a replacement battery to avoid getting stranded?
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I also have an '18 E300 delivered in July 2017 that had the battery replaced in December 2021 at 4½ years. I got low battery warnings, but was never stranded. IIRC the car had 15k miles.
Last edited by ua549; Sep 14, 2023 at 03:43 PM.
Thread Starter
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Joined: May 2003
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From: Long Island, New York
2018 E400 4matic Wagon
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From: Long Island, NY
2019 E 450, 2016 E350 4matic (retired), 2018 Ford Edge Sport, 2008 Porsche Boxster
Both in the spring and the fall, I put a battery charger on it. So far so good!
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From: New Jersey
MB W213 E300 4MATIC Luxury Model
I have a 2017, in it’s 7th year. Didn’t drive a lot when Covid started. Received the change battery notification a couple years ago and started to use a tricycle charger. If I play music for an extended period of time while the car is off I will receive the charge notification. Car is driven more frequently now so don’t receive message that frequently, just passed 35,000 miles a couple weeks ago.
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From: Hermosa Beach, California
2018 E400 Coupe
I bought my 2018 E400 Coupe on November 3, 2017; it was brand new. The "on-board electrical system battery" was replaced on October 4, 2021, because the car would not start. At that time the car had only 11,412 miles on the clock (I stopped driving for business in March of 2020 due to the pandemic, and the lack of use may have had something to do with the battery's failure). To their credit, my Mercedes dealer did not charge me for the replacement of the battery or the associated labor.
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You were still within the 48 month warranty period. Lucky you.
I was just out of the warranty period and it cost several hundred dollars for the replacement and labor.
I was just out of the warranty period and it cost several hundred dollars for the replacement and labor.
Last edited by ua549; Sep 15, 2023 at 06:52 PM.
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From: New York
2018 E43
I replaced the battery on my 2018 last fall. No warning lights but wanted to get it done before winter. You'll notice the start/stop stops working towards the end of the battery life. Replaced with a larger AC Delco battery from Advance Auto with no issues.
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From: Venice Florida
2018 S560
I think my main battery has had slightly lower voltage the past couple of years as the start/stop started working intermittently then and now never works so I've got a spare voltage regulator just incase but pretty sure it’s the main battery causing the issue but I don’t care though it’s nice to have the start/stop default to not working anyhow. The car is on a battery maintainer 6 months out of the year. I’ll just leave it as it is until it doesnt start who knows maybe get a few more years out of the main battery. Seems like these cars are very sensitive to looking for a high battery voltage to make the start/ stop functional.
I’ve had the battery tested twice at batteries plus and they claim it’s fine. I figure why replace a battery over the start/stop feature that I don’t want anyhow?
I’ve had the battery tested twice at batteries plus and they claim it’s fine. I figure why replace a battery over the start/stop feature that I don’t want anyhow?
Last edited by 2012 merc amg; Sep 18, 2023 at 12:11 PM.
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From: San Francisco, CA
2017 E300
this! start/stop stops working, then you know!
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From: Venice Florida
2018 S560
But my point why replace a battery over just the start/stop feature not working? Everything else works. It's good to have the start/stop feature disabled, I'll take it. lol
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From: Hermosa Beach, California
2018 E400 Coupe
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From: Venice Florida
2018 S560
Yes that’s what I always did before start/stop defaulted to not working. Everything else works fine distronic, brake lock etc. seems like in the cars that use the aux battery these other things don’t work plus you get the aux battery malfunction on the middle display.
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2018 E-300 4matic Sedan
My car is five years old, and I haven't noticed any battery issues. The start/stop feature doesn't activate very often, which doesn't bother me. The fact that it still activates occasionally makes me feel more comfortable that things are still acceptable.
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From: Venice Florida
2018 S560
At least with the newer cars in e class 2017 and up use a little black box buried inside the passenger footwell. My understanding is when these go you will loose adaptive cruise and the brake pedal lock up feature and start/stop totally plus get a message on the dash saying Aux battery malfunction. I guess these can go out anytime over 3 years or so so that’s why I bought a spare to be prepared for when it does go. I do like this setup better than the small aux batteries used in other models like my 2018 S class. They are definitely only good for 3 or 4 years and even more tricky to swap out. I got the one for my e class 30 bucks on Amazon. The battery in my S class was 100 bucks at batteries plus and then an independent place charged me 100 for the install. So in answer to your question these aux devices control some of the secondary feature of our cars. I don’t know the answer as to why these can’t all be controlled by one main battery but I sure wish they were it would make life with a Benz less worrisome and simple. If anything Benz should have not buried these 4 year maintenance items making them so inaccessible. Maybe it was a plot to get people to get rid of their cars every 4 years or so and buy a new one. If I were more young and adventurous I might just run the positive and negative wires of the aux battery to the main battery and see how that worked out and then only have one battery to worry about like most cars.
Last edited by 2012 merc amg; Sep 19, 2023 at 10:54 PM.
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From: San Francisco, CA
2017 E300
I know the aux malfunction message is quite common. interestingly, I did get that message maybe a year ago and it came on a few times, but then it went away and never came back.
Thread Starter
Super Member
Joined: May 2003
Posts: 967
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From: Long Island, New York
2018 E400 4matic Wagon
I have a 2017, in it’s 7th year. Didn’t drive a lot when Covid started. Received the change battery notification a couple years ago and started to use a tricycle charger. If I play music for an extended period of time while the car is off I will receive the charge notification. Car is driven more frequently now so don’t receive message that frequently, just passed 35,000 miles a couple weeks ago.
Last edited by Long Islander; Sep 20, 2023 at 04:30 AM.
Thread Starter
Super Member
Joined: May 2003
Posts: 967
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From: Long Island, New York
2018 E400 4matic Wagon
What size battery did you replace the original battery with? I noticed some sites list an H-8 battery as fitting, but I don't see how it would fit in the small space on the passenger side of the engine compartment.
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From: Venice Florida
2018 S560
No I bought this one. Boskavalo voltage converter module. Looks like the one you posted should work though.
looks like they are all similar. A lot say they will only work up to model year 2018 but also list they will work with the E450 which didn’t come out until 2019. I leave it in the car so when I do get the aux malfunction warning eventually I’ll find a Indy shop to swap this part out. Simple one wire plug to install it. It’s just you have to take apart the passenger side footwell panels to get to it.
looks like they are all similar. A lot say they will only work up to model year 2018 but also list they will work with the E450 which didn’t come out until 2019. I leave it in the car so when I do get the aux malfunction warning eventually I’ll find a Indy shop to swap this part out. Simple one wire plug to install it. It’s just you have to take apart the passenger side footwell panels to get to it.
Last edited by 2012 merc amg; Sep 20, 2023 at 08:35 AM.
