Tom in Austin

This is my first car with an AGM main battery and it's the original item from the 5/2016 manufacture date, so just now passed six years of use. I have about 45,600 miles on the car.

The car starts fine and everything works fine, but my past experience is an old battery often goes dead suddenly with little warning. The only thing I've noted in my year and a half of ownership is the car rarely ever goes into "auto stop" at stoplights, and I believe that behavior is a sign of a weak battery.

In other threads on this subject people say their main battery lasted longer than six years, so is mine likely to keep going a while longer, or should I go ahead and change it now to be on the safe side?

Nice Ride

Start / Stop is related to the AUX battery, as is many other items. Mercedes has the equipment to do a proper test of the battery, it cannot be done properly without the proper test equipment.

chassis

4 years is the beginning of the window for battery replacement. At 5 years/almost 100k miles my main battery started giving slowish starts in cold weather. I preemptively replaced it when it was 5 years old.

amgs63dxb

Main battery prod date 08/13... (W222 Edition 1) still going strong (I drive the car mainly on weekends, so it's parked week after week).
I replaced my aux battery (same date) last year though... Which is interesting, because normally the main goes first. 41k miles...

SilberGrau57

You could always throw one of these in the trunk if you're worried about getting stranded. It will crank a gas engine up to 6.0L or diesel to 3.0L. $100 on Amazon.

Diesel Benz

My W222 was almost 8 years old with the original main battery and it was just fine. Changed the AUX battery the second time just before selling the car.

1bad540

so original batteries will go 8 yrs often...but generally 5 after that. I changed my aux battery last summer when the msg came on the dash. I would change the main the 1st time the car gives a slight slow crank. mine is a 15 w 50k.

Quadrobenz

Here is my experience with 5 MB's with AGM batteries. The length of reliable service seems to be related to the usage and duty cycle the batteries experience. For example, my 2015 S65 (about 45k miles) still has the original main AGM battery. The aux battery was replaced in 2019. The S is only used for long commutes and trips. When it is started it runs for at least an hour. It will then sit for three or four weeks until the next long trip. Never had to charge it or use a trickle charger. My wife's 2018 E63S is on its third AGM. That car is used only for short trips, like to the grocery store or the hair or nail salons. MY 2017 S65 (11k miles) is also on its third AGM, again its usage is mostly short, local trips. All the batteries that were replaced tested OK until the Battery light came on in the instrument cluster, then they did not test OK and were replaced under warranty. In my experience, if the battery warning light is not on then the battery will test good, even if it then fails the next week.

Mitch Alsup

I have a 2015 S-600. It is on its original man battery but on its 3rd aux battery.

Tom in Austin

Great info guys, thanks!

I kinda suspected how the car's used has a lot to do with it. My driving is a lot like Quadrobenz's so I will stick my neck out and predict there's more life yet in the main battery. Only big difference is the Texas summer heat!

SilverArrow44

My car reached the 4 year mark in late October 2021. When I dropped it off for regularly scheduled service and some final warranty repairs in early October 2021, my service advisor at Mercedes-Benz of Austin reported that the battery tested good, but that I should consider replacing it in the months to come due to its age. Before he mentioned it, the issue was already on my mind because I've never had a battery in any car last longer than five years. The battery in the S-Class is in a well insulated trunk, so it's protected from the elements, but I still wanted to avoid the risk of being stranded and left waiting for AAA. So in December I chose to replace the main battery and the auxiliary battery myself - bought both at Advance Auto Parts. The replacements were identical to the factory batteries, but with longer warranties.

Tom in Austin

Thinking about the main battery again ... opinion seems about 50/50 whether you need to have the computer reset after you change it. My assumption is, if you don't reset the computer and the car charges the battery in a sub-optimal manner, the only consequence is the new battery might not last as long. I doubt sub-optimal charging would have any effect on driveability or on the health of the rest of the car.

Since getting the car into a service bay to reset the computer would probably cost as much as another H8 AGM battery, is it really worth it or take my chances with the lifespan of the new battery?

Mitch Alsup

The main battery in my 2015 S-600 is still operating.
{However I have had to replace the auxiliary battery twice already.}

But, yes, they are know to work and work and work, and then bang -- no workie.

Mitch Alsup

Battery manufactures state that you should trickle charge a new battery up to 100% charge (a deep charge) before putting the battery in the vehicle.
One motorcycle battery manufacturer states that if you don't you may loose up to 15% of battery capacity, instantly.

zitsky

When we talk about replacing battery, are we referring to TIME or MILEAGE? Because I just bought a low mileage 2 year old S560. I got into the habit of replacing the main battery on my Buick LaCrosse every 3-4 years.

miltownhpt

So there was a crazy bad storm last month where I ended driving through what I thought was a deep puddle due to poor visibility … but ended up being deep enough to where I know the car had no contact with the pavement for about 20-30ft and though I got to the end of the water, my engine stalled. Everything else worked. I shut the car off and tried to restart it but there was no crank although everything else worked fine. Long might but ended up getting a tow back home.

Let the car dry out the next day with the hood open with the trickle charger for at least 8hrs. Still no start. A little crank but not enough to start then no crank after a few times of that. Said skip it and asked my neighbor to give me a jump from his car… started in 30 sec. Water shot out from the hood area and sputtered out of the exhaust for about 5min. Let it run while parked for about 15min and drove it for about 10min and made it back home as it felt like it was losing power again. Put the regular charger on it overnight. Started with no jump the next but it hesitates and also I have to start it without the start/stop button and turning the key. If I try starting with the start/stop button it either will barely start or crank a little and fail. So was able to drive like that for about a week or so, weak start but car drives normally otherwise. Went to the dealer and they were booked like 3wks out. Took it t batteries plus and confirmed voltage and alternator is fine but battery test failed for not hving enough cranking amps which what I figured. There batteries are $240 with free install, dealer it was either 399 or 499.

If they use an aftermarket battery is programming or calibration needed? The advisor at the dealer said prior to 2016 I believe they did not …although I think he is thinking using an OEM battery. I have a 2014.

zitsky

Wow thank you for making me feel better about my three week old S560. That… was not wise.

danvel223@

HI there ,

I am new to all this so please excuse my question . Is this ( battery ) the battery the Trunk of the MB and not the one under the bonnet . I take it the Auxillary battery never gets boosted by a Noco Booost plus ? tia.

blackbullit

I need to replace my main battery.

I want to clarify if the main battery is a H8 or H9. AutoZone lists both for the S560.

Which is correct?

blackbullit

I answered my own question.

Bought a Duralast Platinum 9H AGM battery at AutoZone for $239. Dealer was charging $488 for OEM battery.

Works well with no issues.

Tom in Austin

Picked up an 'Everlast' H8 AGM replacement battery at WalMart today for $169. Have it on the trickle charger tonight and it goes in tomorrow morning. Looking forward to having auto-stop working again and avoiding a surprise dead battery one day. I also think the weakness of the main battery may be why my dash display keeps fussing about changing the battery in all my keys, and then showing 'Key not Detected". If the key can't talk to the car, it may be key battery or it may be the car.

Curiously enough, the new main battery is marked "Made in Germany" ... perhaps made by the OE supplier to Mercedes, wouldn't surprise me ....

Follow up, car runs perfectly with the new battery and autostops regularly now, just like it's supposed to. Also seems to be showing higher gas mileage, though that's very preliminary observation. Still fussing about key batteries, so will put in yet another battery in each key and see if it finally shuts up.

cfmistry

To bring some light to this thread…

My “main / starter” battery was the original made in 1/2015 so it made it almost 8 years.

No issues starting or running it down. Zero issues. But BenzNinja did some work on my car and told me the battery only charges to about 11.3V. He told me to change it quickly, so I did. $240 DieHard Platinum AGM H8.

So the point of all this is… if you’re in an older W222 on the original battery, it’s probably time to change it.

S_W222

Mine had lasted all the way from end of 2014 until 2021 when I bought it. The only times when it gave up is in the winter of 2020 when I had it garaged for a month, but after only drive at moderate speed, the battery charged itself and I never noticed the battery low voltage message ever again. At that time, I had over 72K miles on it (2015-2021). Not sure if it is still running to date.

Merserybenze

2018 model in service end of 2017- over 5 years old. 60k still going strong. Replaced aux battery at 50’ish K and just under 5 yrs. Florida car so no really cold temps.

zitsky

Die Hard? Is that the one that Bruce Willis recommends?