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Is there an easy or obvious way to tell what type of 12 Volt battery is in our cars? According to the owner’s manual it could be either. The reason why I ask is that Mercedes’ trickle charger has two modes: one for AGM and another for Lithium.
I think the only way to find out would be to remove the rear trunk liners to see the battery for yourself...
That should be the easier way than finding the capacity for both battery types and performing a load test. (assuming they have different Ah ratings)
* BMWs have battery charging management system that specifies AGM or Lithium-ion that is coded.
I wonder if MB has something similar.
Last edited by nearwater4me; Oct 6, 2025 at 05:33 PM.
2023 E 450 Sedan. 2018 GLC 300. 2013 E 350 Coupe (retired)
Search of parts catalog for your car lists three twelve volt batteries. This is what you are charging. Not the 48 volt battery. Call the dealer to confirm. It is AGM. Not sure why you resist this idea, as pointed out to you in your other thread.
On my 2022 S580 the 12V battery is AGM. It was replaced once under warranty. I believe the factory warranty covers that battery. It also failed on my 2021 GLE63S and it was the same exact AGM battery but MB stealership swore it tested good. On the GLE it is under the drivers seat and a pain to replace. Seat and pillar removal along with some duct and other not so fun stuff. On the W223 it is in the trunk. Lift the floor hatch and remove the lower liner (it pulls out with some flexing) and it is easy enough in it to replace.
According to this reference from Mercedes, we have TWO 12 Volt batteries and it shows them as being Lithium. Is one a stater and the other Auxilary? Which one is the trickle charger charging?
2023 E 450 Sedan. 2018 GLC 300. 2013 E 350 Coupe (retired)
I am not sure why this is so difficult for you. Multiple threads asking the same question. You have one 12 volt agm battery this is the one that you can trickle charge. The 48 v battery is for the starter generator, you can not charge that externally.
Last edited by smiles201; Oct 8, 2025 at 04:45 PM.
Those two batteries in the diagram aren’t the 48 Volt batteries but are the 12 Volt batteries. I think the fact that they are charged via the 48 Volt battery is why that 48 is there. So, why is there two and why would Mercedes list them as Lithium in these diagrams. And fact of the matter, no one has presented any shred of proof showing the battery in my car is AGM.
Those two batteries in the diagram aren’t the 48 Volt batteries but are the 12 Volt batteries. I think the fact that they are charged via the 48 Volt battery is why that 48 is there. So, why is there two and why would Mercedes list them as Lithium in these diagrams. And fact of the matter, no one has presented any shred of proof showing the battery in my car is AGM.
In the US a 2023 S500 is still under the factory warranty assuming you are under 50k miles. Have the dealership test the battery and ask the service advisor to confirm as the only proof is your battery in your vehicle. If you want proof of the battery and location of mine I can do that but unless you are next door to me as I have no intention to travel to show you and as such I can not provide proof of yours to you.
FWIW the dealership replaced the one AGM 12V in my 2022 S580 that is depicted as the single battery in the center of the trunk in your diagram in 2023 under warranty. I replaced the same exact model AGM battery in my 2021 GLE63S because the dealer said it tested "good" and I was tired of the low and critical battery notifications in 2024. I have a battery tester and it did not test "good" on my tester. It tested at 550cca. The dealer did not say what it tested at other than "good" when it was not. The battery is about $300 at my local dealership parts department.
The whole reason I’m skeptical of people just saying mine is AGM so yours is too is because of what’s written in the owner’s manual in black and white. That’s the entire reason for this post…why would they say and write that and for what reason would they list two types of batteries and if it’s true, is there a way to know other than asking the dealership or pulling carpet to see for yourself?
The whole reason I’m skeptical of people just saying mine is AGM so yours is too is because of what’s written in the owner’s manual in black and white. That’s the entire reason for this post…why would they say and write that and for what reason would they list two types of batteries and if it’s true, is there a way to know other than asking the dealership or pulling carpet to see for yourself?
Google has conflicting information as well.
I wouldn't fully rely on AI results. I wish I can turn it off, many times I find Google's AI providing inaccurate information.
2023 E 450 Sedan. 2018 GLC 300. 2013 E 350 Coupe (retired)
All mercedes 12 volt batteries are agm and have been for years. There is a small secondary battery or inverter in some models. The 48 volt battery is with the mild hybrid cars and is not accessible for charging. You need to talk to a local mercedes mechanic to get straightened out.
2019 AMG S 65 and too many other vehicles to list here in this small box
Originally Posted by Frenetic
I wonder what model has the 12 Volt Li battery and why they would even mix and match.
More premium models have a premium battery.
There's a $1700 difference in the battery technology. And don't think it's all about weight savings as that is really just an additional side benefit to Lithium batteries.
You can look at your VMI and determine what type of battery was installed in your vehicle. If you don't have one, ask your stealership for a copy.
Like most things MB, it's difficult to build or get a list of the vehicles built with a Lithium batteries. From what I have seen, it appears that when the vehicle window sticker has a price that starts with a "2" it almost always has a Lithium battery.
2023 E 450 Sedan. 2018 GLC 300. 2013 E 350 Coupe (retired)
Sorry Frenetic, I apologize, I see your point now and I am confused as well. No idea why they would say agm or lithium. You would think it would be the same for each car! This is what i suppose, but could be totally wrong: First, the diagram with the yellow battery markings I believe is showing the location of charging points under the hood for the 12 volt, the actual 12 volt is in the trunk. I believe the 48 volt battery is lithium and is located under the charging posts under the hood. The only way to know for sure is to look at your battery in the trunk, which has easy access. Not sure how easy it would be to get a look at the 48 volt battery under the hood. What they label as capacitor acts as a third power source used for only a few functions. On my E450 I use the charging posts under the hood and set the charger to AGM.
Last edited by smiles201; Oct 11, 2025 at 07:56 AM.
There's a $1700 difference in the battery technology. And don't think it's all about weight savings as that is really just an additional side benefit to Lithium batteries.
You can look at your VMI and determine what type of battery was installed in your vehicle. If you don't have one, ask your stealership for a copy.
Like most things MB, it's difficult to build or get a list of the vehicles built with a Lithium batteries. From what I have seen, it appears that when the vehicle window sticker has a price that starts with a "2" it almost always has a Lithium battery.
Now this makes sense to me. I think Mercedes made an oversight not explicitly listing which models have what.
Here’s another question: are the same “expensive” models the ones with multiple 12 Volt batteries or do all S classes have them?
2023 E 450 Sedan. 2018 GLC 300. 2013 E 350 Coupe (retired)
I just discovered that you can buy a 12 volt lithium battery for your MB. Not cheap. Do some AMG's come with a lithium 12 volt battery standard? Big weight saving, 3 or 4 times more expensive then AGM.
Last edited by smiles201; Oct 12, 2025 at 09:23 AM.
2019 AMG S 65 and too many other vehicles to list here in this small box
Originally Posted by Frenetic
Now this makes sense to me. I think Mercedes made an oversight not explicitly listing which models have what.
Here’s another question: are the same “expensive” models the ones with multiple 12 Volt batteries or do all S classes have them?
YES. Multiple 12V batteries installed. Large Lithium Ion Starting battery AND a small (motorcycle size) Auxiliary 12V AGM battery for accessories.
And yes, they are interconnected through an elaborate control switching scheme for charging and use profiles. Discussed on the forum in multiple threads. Suggest using the search feature.
Keep in mind that the S Class Owner's Manual is for ALL S Class vehicles made for that year/quarter it was published. MB does not have multiple S Class manuals based upon each model ordered so they require overlaps to cover all iterations.
You can also find articles posted about method to replace auxiliary battery without loosing memory settings.
Much information here on the forum about batteries if you look for it.
There are some 12V lithium batteries, such as the Antigravity brand, that have internal battery management systems and are promoted as plug-and-play -- apparently this type can replace an AGM type without any coding changes necessary to a car's battery management system. I recall a forum thread quite some time ago in which BenzNinja indicated he could code a MB with a 12V OE lithium battery to accept a conventional AGM instead (please correct me if I recollect incorrectly!).
2019 AMG S 65 and too many other vehicles to list here in this small box
Originally Posted by streborx
There are some 12V lithium batteries, such as the Antigravity brand, that have internal battery management systems and are promoted as plug-and-play -- apparently this type can replace an AGM type without any coding changes necessary to a car's battery management system. I recall a forum thread quite some time ago in which BenzNinja indicated he could code a MB with a 12V OE lithium battery to accept a conventional AGM instead (please correct me if I recollect incorrectly!).
The vehicle battery management system works with specific window of operation for each type of battery. Based upon your VMI configuration, the vehicle is programmed to support the battery type installed from the factory.
That's correct in that Peter @BenzNinja can modify your setup to change from the expensive Lithium to a standard AGM battery.
Cost being the primary reason people consider this modification but I just can't get the math to work good enough for me.
As I hope to get a good 15 years out of my OEM installed Lithium battery by good care and feeding. The AGM battery will need to be replaced every 5 years.
Factor in the labor and hassle cost of changing out the battery twice after the original AGM failed is not a task worth the loss of benefits the Lithium battery provides.
Play with the numbers all you want and it still just doesn't add up the same when comparing the two options.
The numbers work out opposite for me with an OE H8 AGM battery versus replacement with an Antigravity substitute. An auto store top of the line H8 AGM battery (100 AHr / 900 CCA) costs $250, with a 3 year replacement warranty. The Antigravity H8 lithium (80 AHr / 2000 CCA) costs $1350, with a 3 year replacement warranty extended with a 2 year proration (5 years total). Assuming the AGM needs replacement after 5 years, that's $500 for 10 years of service. Antigravity says 7-9 years life can be expected (let's say 10 years). For me the Antigravity battery is a bit more than 2.5 times as expensive over 10 years. Although the next time I have to hoist that 59 pound AGM monster out of the cargo floor, I might become lithium believer at any price!
2019 E 450, 2016 E350 4matic (retired), 2018 Ford Edge Sport, 2008 Porsche Boxster
Originally Posted by streborx
The numbers work out opposite for me with an OE H8 AGM battery versus replacement with an Antigravity substitute. An auto store top of the line H8 AGM battery (100 AHr / 900 CCA) costs $250, with a 3 year replacement warranty. The Antigravity H8 lithium (80 AHr / 2000 CCA) costs $1350, with a 3 year replacement warranty extended with a 2 year proration (5 years total). Assuming the AGM needs replacement after 5 years, that's $500 for 10 years of service. Antigravity says 7-9 years life can be expected (let's say 10 years). For me the Antigravity battery is a bit more than 2.5 times as expensive over 10 years. Although the next time I have to hoist that 59 pound AGM monster out of the cargo floor, I might become lithium believer at any price!
Actually the H8 battery at both Costco and Walmart is $179 not $250. The Walmart battery is warranted for 48 months, the Costco for 36 months.
I agree about the weight of the AGM H8: to solve that problem the $179 at Walmart includes installation!
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