dead battery this morning
 

So my 2011 E550 wouldn't start this morning. Started fine Saturday evening but I didn't drive it at all on Sunday. No sign that I left any lights or accessories on. Maybe it's just time since the car has been in service for 50 months (you know - just outside that warranty period and so the timer goes off).

Was able to get a jump from my other car. Drove it around for only 10 minutes to drop someone off and then turned it off. My mistake as I meant to run it for 15-30 minutes - just wasn't thinking. So an hour later it didn't start again. It's sitting at home right now waiting for me to get home. Then I'll jump it again and drive it around a little to see if that does the trick. If not, then I am off the get it tested.

I am doing my research now to evaluate possible replacement options. Here is what I have found so far:

1. local MB dealer - $350 (with 2 year warranty)
2. Interstate battery (MT5AGM) from local tire place - $300 installed (6y prorate warranty with 100% covered for first 2.5y)
3. Autozone - Duralast Platinum H8AGM - $172 (5y prorate with 100% covered for first 3y)
4. local Indy shop - estimated $250 installed (unknown battery type, warranty depends on what he buys)
5. Sears DieHard Advanced Gold AGM Battery - Group Size 49 - $190 plus $20 install (3 yr full warranty, no prorate)

From what I have read on here, there seems to be no advantage to using the dealer. They are more expensive and doesn't come with a better warranty.

I am tempted by Autozone's price and warranty, but has anyone had any experience with them on a battery purchase and install? Any other recommendations I should look into?

Also, from what I have read there seems to be some debate as to whether the W212 needs any special programming or reseting of windows, etc. after battery replacement. Anyone who has had one replaced care to comment?

I would probably get the specs of the MB OEM battery and make sure that the battery I selected at least meets these specs.

Good point. The OEM battery is 800 amps. All these equal or exceed that. When I spoke to my SA about their price and their warranty, he commented that non MB batteries supposedly have a smaller electronic tolerance or something like that. He didn't know more but heard that's why theirs are the best.

I'd probably just go to the dealer and replace it....my daughter had her 4 year old battery tested after having a start issue. Checked it and they said it was fine. I told her replace it regardless....but they said it was ok Etc etc. Fast forward 2 months, stranded at a gas station....won't start, this time she replaced the batt :-) good luck

BMW battery is a big deal with Battery Registeration and price running around $600 installed but not with MBZ battery. If spec. meets or exceeds MBZ, you shoud be home free.

Do you own a trickle charger? Maybe put it on for a couple days to see if you can get it to come backbto life. I have had some good luck with this and a Ctek charger/maintainer. You know quickly if its shot.

Don't own a charger but maybe I should buy one after what I learned tonight.

So obviously I had to jump the car when I got home. Took it out on highway for 30+ minutes of driving and stopped by local autozone on way home. Left car running and popped my head in to ask for a battery test. Guy comes out with handheld tester and hooks up with car running to check alternator first. Says that's alright then has me turn off car to check battery. Battery comes up as GOOD but needs charging as it was only at 28%.

I was surprised - had he told me it was bad I would have gladly bought a battery (incidentally he told me they change batteries on a lot of MB in this neighborhood. They have memory minders to keep setting while changing out.) Always appreciate when someone doesn't try to sell me something I don't need. He offered to charge the battery for free but said it would take 2 hours to get it close to 100% and they closing in an hour so I'd have to come back tomorrow. So I browsed their chargers which were about $60 or so. Then I remembered folks posting here about decent chargers for less $ so I left the store. To my surprise, the car started right up.

So charging may be the answer. But I still don't know what got the battery down so low in the first place. The guy told me that the alternator can only recharge a battery so much and that I should invest in a charger to really maintain this battery (and take some stress of my alternator).

Your batter sounds like it is not holding charge! If that is the case, all you have to do is replace it with new one.

My theory is it's the "smart" charging system. "Dumb" charging systems attempt to keep the battery fully charged but "smart" systems only charge when a low level is reached. This is designed in and helps gas mileage by reducing the load on the engine. I can't believe it saves that much gas to be worth the down side of batteries not lasting as long though. I came to this conclusion after very closely monitoring my battery (both old and new) health with a DVM. Alternator output around 14.5V and no matter how long I drive the battery slowly retreats to about 25% charge before charging again but it never gets close to 100% no matter how much I drive. My old (2001) Benz stayed fully charged as long as I drove it more than 20 miles. My wife's 2010 BMW has the same charging characteristics as my E350. I use a battery tender about every other week on the E now.

Well I do drive mostly short trips. Commute is 6 miles each way and some errands are within 3 miles of house. Sounds like I may need to invest in a charger. If the battery ends up not holding the charge, then I will replace it anyway.

Most important question is will it start for me tomorrow. We'll see.

I ran into the same problem weeks ago. Car wouldn't start at times (happened 3 times until I decided to get a new battery). I noticed that I had problems starting after short trips. Anyway I went to a trusted local tuner shop and they ordered an oem battery and installed for $320. I have a 2010 so I figured it was already time for a replacement. Haven't had any trouble since.

Does anyone know if you should put charger/maintainer (like Ctek) on both batteries (under hood and in trunk), or will both be charged if you only connect to the one under the hood?

I used to use trickle charger with BMW battery in 528i but not in MBZ.

I had no idea there were two 12V batteries in the new E-Class. My '10 has one battery under the hood and then a small battery under the dash that is used only to operate the electronic gear shift. My '04 W211 had the main battery in the trunk, as well as the smaller battery for the SBC braking system under the hood.

I would not think that connecting the Ctek charger to the battery under the hood would charge anything but that particular battery. I'm not sure I would risk connecting the trickle charger to anything but the main battery while it's in the car. What is the purpose of this battery in the trunk on the new models?

Front battery, follow jump start recommendation in manual (trunk is ECO start).

OK, this begs the question:

Should the owner of a 2011 E550, who drives it a lot with overnighters in places far from MB dealers, or whose wife drives it a lot alone, buy a new main battery after 4 years just as a preventive measure.

Or does the test performed at the dealer really give an indication of expected battery lifetime and reliability?

Or are the incidents we are hearing here outliers and the batteries should last a lot longer?

Further, is the main battery covered in the extended warranty period, or is it considered and expendable?

ECO start battery. Got it!

I believe the Eco battery also eliminates the need for the under-dash battery for electronic gear shift.

Thanks for that info. So I take it there are no instructions for using a battery charger/maintainer for the ECO battery and it is not recommended, or necessary to do that?

So the car started fine this morning and again after work. Naturally I am being more cautious and turning off the climate before shutting off car so there is less load on battery when starting.

Took it over to a tires plus near work. They tested the battery and confirmed it is good and just needs charging. They also checked the alternator and it was fine with no load and under load. Their test said the battery had 571cca which they said was 80% of the 700cca rating. So they told me just to drive it around as it is nearly fully charged. They suggested I bring it back in a few days for them to check again to see they charge level then.

So I headed home and stopped by the same autozone on the way 10 minutes later. Last evening my battery was at 28% (cca unknown) according to their tester. They checked it again and it come up at 40% and they advised to charge it.

Not sure why one tester would show roughly 80% and another 40%. Kind of mixed messages. At this point I plan to see how it starts on its own and get it checked again in a few days. If its near fully charged, I will move on. If not, then I plan to get a trickle charger and see how it does then.

There is nothing wrong with preventive measures. I could just buy a battery but everyone tells me it's fine. Fortunately, I am near help if I need it. Nothing wrong with just replacing it for peace of mind.

From what they told me, the test just checks the current condition and whether or not the cells can be recharged. The battery could go bad in a week even if it tests fine today. If you want some security you may want to look into one of the emergency jumper packs and keep it in your trunk. I don't have one myself, but a coworker buys one like this for her parents and kids. It plugs into the car outlet to keep it charged and you connect the clips to the battery when needed for a jump. You could keep it in the trunk and use the outlet there. Can't vouch for it myself if it has enough juice for our cars.

Even MB ELW excludes batteries. Only the B2B covers them.

My battery was replaced under regular warranty at three years. I was getting my wood replaced and mentioned my car seemed to struggle a bit starting the last couple of days and I thought it was the battery. I believe they know the 'smart charge' "feature" has unintended consequences.

I was in the same situation with OP a week ago and I was going to purchase an after market battery for $180. Then decided to take it in to MB and they found out the alternator was not charging the battery properly. So MB replaced my battery and alternator all under warranty. So sometimes it is good to bring it back to MB to have the proper diagnose.

Forgot to mention my car is out of warranty. If it was under warranty I would have definitely taken it to MB.

I would recommend the CTek brand of chargers. The base model is fine. It will bring your battery up to full charge in 1-2 days. Then you should be ahead of the curve for awhile.