This has happened to me a couple of times in the last week and so far I'll try to start the engine and instead of turning over once and starting it keeps turning over every second like its on a repeated type of cycle.

I thought maybe the computer was a little off so I got out of the car turned everything off shut the doors locked the doors unlocked the doors then got back in and tried it and it started no problem.

Yesterday I stopped for 10 minutes to check out a condo and came back to my car and it would not start it was doing the same thing all over again every 1 second trying to turn over. But I manage to jump it with one of those tiny little hand held power boosters that I have It is the size of a small paperback book.

Anyway I'm going to replace the battery today from auto zone as I noticed that the date code on it says 23rd week of 2013 which makes it 5 and a 1/2 years old. I have never had any car battery ever last me more than 3 years down here in Florida but was unsure about the age of life expectancy for Varta batteries.

Anyway I have 2 questions for all of you 1st question is is this normal life expectancy for these batteries? Also I cannot find my battery anywhere at Sam's club , Costco, or Walmart or even optima on their website says there is not a battery available from my car or even my daughter's C class was just blows my mind because these are 2 very common cars on the road.

So what is so special about these cars and this battery that hardly anyone else seems to have one?

Mercedes wants $350 for it only 2 year warranty but I think I'm going to take the $190 route from Autozone.

I would get the Mercedes $150 coupon and get it from Mercedes

battery life is usually the free replacement warranty period and maybe a little bit more.

Anything longer is possible but ya never know.

Have battery tested first by auto zone then replace if bad as could be something else.

While the coupon works on the battery, it's still cheaper at Autozone, Advance Auto or Pepboys. It's an AGM battery so yeah, Costco, Walmart and Sam's don't carry the AGM, but they carry the regular battery. The AGM is supposed to last longer. It's more like the charging algorithm is less generous to the battery these days. The AGM battery in my 2008 is still OEM and it's over 11 years old at this point. The one in my W212 was already replaced when I bought it. Check retailmenot.com, they usually have coupon codes for Autozone which is normally 20% off and Advance has 25% off, Pepboys is about 25% now. I'd consider the Pepboys one if there's one near you. They have a 4 year warranty, Advance and Autozone is only 3 years. Pepboys is slightly more though.

Or just go to the dealer, load up on snacks and get a free car wash while they do everything. All those places you'd have to install the battery yourself. Several of them use to install for free, but I guess there were too many screw ups with Mercedes so now they either charge extra or won't do it on an MB.

Good recommendation My dealer told me mine was bad 6 months ago and I went to Advanced Auto and they tested it was good.

The Pep Boys Bosch AGM battery was as much as the dealers installed.

Yeah, not worth the install price. I've done mine a few times just to take it out and charge it up. Those batteries are heavy, but if you're able, it's not a big deal to install yourself. It's pretty simple to install, only way to screw it up is to install it backwards or disconnect the positive first instead of the negative. Always disconnect negative first and connect it last.

The $150 off $300 makes it competitive with the dealer, otherwise the dealer is normally the most expensive.

I would go genuine MB if possible - they install some ridiculously quality batteries from the factory. The original on my '09 C300 lasted 9 years before it needed replacement, when I replaced it the aftermarkets at Autozone or Pep Boys were not much cheaper than OEM so I just went with another OEM.

My vehicle was garage kept with about 9.000 miles at 4years and that is all I got out of both OEM batteries. They both were gone. Got replacement from pep boys and they are Guaranteed longer than the OEM battery from Dealer. I installed myself and it took about 15 minutes. Dealer wanted over a hundred to install because he said you had to keep it charged while switching out the battery. That was bull. Took battery out then drove to pep boys and drove back with new battery and installed. Never lost any data. Just a gimmick for dealer to justify the price they charge.

I suspect MB did something with the charging algorithm in the W212 vs the W211. My W211 battery is over 11 years old and still going. My W212 already had the battery replaced by the previous owner after about 4 years. I bet if you gave the battery a good charge a couple times a year, it'd last a lot longer. My theory is that it just doesn't charge it enough, probably some trick to get better CAFE numbers.

As for the types, the Varta OEM battery is Johnson controls and batteries from Autozone and Advance Auto are also Johnson Control batteries. I believe Pepboys carry both, the Bosch is Exide and the Champion is Johnson Controls. Exide had to file for bankruptcy a few years back as Walmart dumped them as their supplier.

W212 is having so-called "smart charge system" what suppose to save fuel.
I drive lately with DPF gauge and as side monitor voltage and don't see anything smart about it. After morning start it charges at 14.5V, what is killing voltage, only later in the drive to switch to 13.6 or plain battery power at will.
So no-so-smart charging is killing the batteries. I did not see them lasting longer than 4 years in those cars. Than again, if you save fuel this way, maybe it makes sense.
The only data you lose by disconnecting the battery is window/sunroof synchronization and time zone on your command center.
I just did that couple days ago and car learn the time somehow, GPS ? But was 1 hr off as time zone was wrong.

I heard all the horror tales of what it took to change a MB battery when I did it myself on my W204 C300.......I didn't have to reprogram the stops on the auto-open/close windows or sunroof at all and everything worked just fine after the replacement. The hardest part of the whole operation was lifting that massive battery in and out without banging up the bodywork, it is large and heavy AF compared to the seemingly minuscule Toyota or Honda batteries.

What year is your ride that you had to reprogram. It has to be older than my 2014

it is 2014.
Thinking back about it, I am not sure about windows synchronization. For me window synchronization is something done automatically, when I drive, so don't even pay attention.
Had W210 where I was using sunroof twice a year and each time it required synchronization for some reasons. But those are the things that don't stop you from driving.