El Cid

For my 2010 the battery was fully covered for the four year period. Unfortunately it die a week after the four year period up and neither dealer nor MBUSA would allow any credit. SA said if had died two week earlier, would have been replaced at NO cost.
I have used Advanced Auto parts batteries for decades with no problems, but not in an MB.
From all I read, I seriously wonder if German engineering is better or just more complicated.

Critter

700cca is the factory "just enough"
Replace with 800-950cca, these cars are power hogs
AGM of course

belarus27

by the way, did you ever had any start up issues , the car would be cranking longer to start?

thefisch

I haven't noticed longer startups recently. There have been a few instances in the past 9 months after running accessory mode when the engine off were I thought the startup with keyless go was a moment longer than normal. But it started on the first try.

Tjdehya

I have a 2011 E550 also. The battery died on me a few weeks ago. I jump started it and drove it home.
I used a charger to charge the battery to 100% and I have not had an issue since.
I almost bought a new battery but I don't need a new battery at this time because it is able to hold a charge.

Hifidude

I might call the 1800 number for Mercedes. Have heard it is sometimes cheaper for roadside assistance to come out to your house and change the battery.

Certainly a lot more convenient.

Alex.currie44

The conversation re the number of batteries is interesting.
My 2003 w211 had two batteries and presumably the 2009 one as well.
When this discussion started I asked my dealer parts guy to confirm the number of batteries in the W212 2011 E350 wagon. He says there is only one.
Any other views specific to the 2011 W212?

RSIKR

One. Under the hood, passenger side directly in front of the glove compartment concealed by a plastic cover.

The 2014 has two, one as yours under the hood and the second about the size of a motorcycle battery in the spare tire compartment for the ECO Start/Stop system.

cetialpha5

Actually they went to one battery in 2007-2009. The 2nd battery was a backup for the SBC system which they got rid of in 2007 so no 2nd battery. Also the usual places like Autozone have online discount coupons code which you can use and find in the usual places like retailmenot and through other google searches. I think once you use a coupon code, it drops it down to under $140. Same with Advance Auto and PepBoys also carries it but their discount code isn't as much and they charge more, probably more like $150 or so. Advance and Autozone normally install it for free, some say Pepboys does it for free and some say not, depends whether they feel like charging extra or not. Also with AGM batteries, it's not unusual for them to last 8-10 years, but depending on how hard you are on the battery, it could die sooner. A cheap 2 amp charger is all you really need to charge up a battery, they can be in the $20-$30 range. Only factor is time, it's probably between an 80-90 amp hour battery so if it were 40% charged, you need between 48-56 amp hours. At 2 amps, that's roughly 24-28 hours, typically a little more than that due to line losses and other reasons. If you got the 10 amp charger, then it could be fully charged in 4-5 hours.

thefisch

Glad to know that AGM's can last that long. Planning on following up today on the battery charge level since I don't have a charger (yet). If I end up needing one, is it better to charge at a slow rate for the sake of the battery (as opposed to time) or is there no harm in fast charging with the battery still installed under the hood?

From browsing options on amazon, it appears there are smart chargers with different cycles for $40 and up. Some are highly touted like the ctek for $55 and up that are pretty much set and forget. Then there are simpler chargers for $20 or more that charge at one rate with no extra bells and whistles. Any advice on which to get? My cars get driven weekly - no seasonal use.

Does anyone know how to check the % charge reliability at home? Most of the chargers I saw don't have any kind of meter. Or do you just hook a charger up every now and then assuming it is needed?

Alex.currie44

The comment re the back up of the brake by wire system is interesting as the service guys on the 2003 W211 said that small battery was to start the car and all the rest of the stuff ran off the main battery.
I like the SBS system back up better. Makes a hell of a lot more sense.

cetialpha5

There are several charts out there that show percentage of charge based on the voltage of the battery. Granted it's supposed to be at 78 degrees without a load on it for a couple of hours so it's just a rough estimate on the state of charge. Just google battery state of charge and you'll find them. Typically 12.6-12.7 volts is fully charged.

On the chargers, anything up to 10 amps is fine, higher than that generates heat and isn't good for long term use. I would just get a smart charger, it will automatically shut off once it's fully charged, those manual ones you have to keep an eye on and you don't want to over charge the battery.

On the W211, you could hit the reset button 3 times once it was showing the temperature and it would give you the voltage of the battery, only worked when the ignition was on, but the car wasn't running. Not sure if there's something like that on the W212. If there isn't, just get a voltmeter.

The SBC system was brake by wire, if the battery died, then you wouldn't have any braking which is why they had the backup battery. It was the main battery that started everything. I doubt the small one had enough CCA to start the car, the main one had 850 CCA.

KEY08

I have brought batteries back to life with the Ctek smart charger. I guess I am done touting the benefits of them. Good luck.

thefisch

So yesterday the battery was still testing good but needs a recharge - still at 40% according to one place and 558cca according to another. So while I wait to pick one out on Amazon, I picked up a Schumacher SSC1000a 10/6/2 at Advance Auto Parts on sale for $40 to try out. At first I was impressed with this unit with the digital readout - it said my battery was at 49%/12.1V. Set it to charge my battery at 6amps. After almost 4 hours it showed fully charged at 100% so I disconnected it and felt pretty good about my purchase. Checked in the morning and the battery was down at 49%/12.1V! So either this charger did not fully charge my battery or my battery cannot hold a charge. Car started fine though.

Tried the unit again this evening but had my mutli-meter with me to check. First thing I noticed is this unit gets above 15v when charging sometimes hitting 15.5V. MB manual says not to exceed 14.8V so this thing is going back. Glad I didn't leave it on overnight.

Going to check out the Ctek chargers - maybe a 3300 for $57 or a 4.3 for $67. Not sure of the difference but will look into them further. Maybe my battery is just months away from dying but will try another charger as this experiment continues. This has been interesting to play around with.

Alex.currie44

I could be wrong but a battery that shows fully charged and only 49% after 8 hrs sitting idle is either got internal problems and is shorted or there is some load of significance drawing it down. You can put a new battery in it but if that doesn't cure it, then you are in for a search of some proportions.

mleskovar

Fully charged = 12.6V.....12.1V is about 30% Hope it's your battery. Sounds like it's sulfated.

thefisch

So I got the Ctek 4.3 charger in late February about 6 weeks ago. Much better build quality than the Schumacher I tried before. Charged the battery overnight but it didn't really need it at the time since the car had been starting fine since early February.

Since then the battery has started the car fine until Friday evening of last week. This is after a normal weekday of several trips for errands, lunch and work that day with no starting issues. An hour after returning from work in the evening, I left home to drop off my kid off to meet friends a couple of miles away. Car started with no issues when leaving the house and there was no evidence that I had left anything on. When we arrived at the destination 5 minutes later, we had to wait for the others to arrive so we stayed in the car for about 10 minutes listening to the radio with the engine off. At first the car was in retained accessory power mode and comand stayed on for about 5 minutes. Then it shut off (as it normally does for me) and I turned comand back on with car off (using the radio on button).

After about 10 minutes when I was free to go, the car was dead. Just a click when I tried to start it. Thankfully my wife was just 10 minutes away so she drove over so I could jump my car after letting her battery charge mine for a few minutes.

When I got home 5 minutes later, my multimeter showed the battery was at 10.7 volts(!) with the car off. Of course it could not start on its own. So I used the Ctek charger a completed a full charge cycle overnight. On Saturday, I tested the battery by starting the car 3 times in succession, turning on the comand/radio for 15 minutes with the car off, and then starting it again for 3 times in succession again. It started all six times with no issue. Battery read 12.4v when not in use, 12.2v when the radio was on. The voltage dropped to 10.5-11.5v when starting and then was at 14-14.7v when the engine was running.

Since I had time on Sunday and didn’t need my car, I put the battery through recondition mode with the Ctek charger. Since that provides over 15v, I disconnected the battery from the car first. That took about 2.5 hours, a short time since the battery was recently charged. Since I have only have a voltmeter and can’t test CCA, I took the car to advance auto to use their tester after the recondition mode was complete. Battery came up good and starting system and alternator (with and without load) were all normal. Battery amperage showed 778CCA on an 800CCA rated battery.

So while I can recommend the Ctek charger, I still can’t understand what caused my battery to be so low on Friday. Perhaps all the short trips I take took a toll over several weeks since the last charge. Or maybe my alternator is having intermittent issues. Unfortunately there is no persistent issue at this point that stands out.

mleskovar

I'm convinced it's the new "smart charging" algorithm being used by German car manufacturers. Instead of keeping the batteries at full charge the level is allowed to drop....to between 1/4 and 1/2 charge.....by my measurements. Before my warranty was up I waited for it to drop to 12.1V and took it in for other warranty service and told them it had 'trouble' starting sometimes (although it didn't). They replaced the battery. With a fresh battery I measured the charge every morning and the same pattern developed as with the original battery.....down to between 1/4 and 1/2 charge although it took a little longer to drop. Theoretically this saves gas because it reduces the load on the engine from the alternator. So if you are down around 1/4 charge and use power with the motor off it wouldn't take long to drain the battery below required crank amps to start the car. My wife's BMW has the same charging characteristics. My last MB maintained a full battery charge as long as I drove it decent miles. Now I use a trickle charger every other week or so. I've researched to see if my theory is correct but found nothing other than the term "smart charge". Anyone know for sure?

porksoda

Battery troubleshooting is fairly easy as long as you have a voltmeter and an extra body to help.

- put voltmeter on battery terminal before starting the car (this gives you the surface charge)
- Start the car and voltage will dip as there is load being added to the battery and surface charge is quickly discharged.
- At this point the voltage should very quickly come back above 12V 13-14V. If it is below 12V then your alternator and or voltage regulator is at fault.
- After a drive you should test the battery's surface charge and it should be betwen 11-12V if it is lower than one of the cells may not be operating properly and it is cheaper to just change the battery.

CCA is crucial for cold climates!

I have had previous vehicles where voltage regulator was working intermittently, which caused drain on battery.

Also if the battery goes below 7-8V there is some damage done to the cells so that should be noted as well.

Battery problems are horrible because tonnes of things go through our heads and it is costly to get diagnosed at the dealer.

Batteries are not that expensive but alternator and/or voltage regulator replacement is a bit more costly.

I live in cold climate and i usually replace battery after 7-8 years, the times i have had battery problems was because of the alternator/voltage regulator.

thefisch

I don't know but your theory would explain what's happened to me. With an older battery like mine (4 years old), it is already holding less of a charge and then not getting enough while running it a recipe for failure. I had thought about using the charger every couple of weeks, but I honestly forgot after the car kept starting with no issue. Guess I need to make it part of my routine before I get stranded somewhere. With past non-MB cars, I would at least get some longer start times to indicate that I was close to trouble. With mine, it went from a normal quick start to click I'm dead in 15 minutes.

Also, I thought the car was supposed to turn off drains when the voltage drops too low. Wonder why it allowed the radio to be on when the voltage dropped too low to start the car.

The voltage readings I mentioned above were done using the two person test steps you listed. After my first sign of battery problems 8 weeks ago, I was routinely checking voltages at night, in the morning, before the door was opened, etc. I was popping the hood and leaving it unlatched so I could get readings without any extra drain from the dome light. For days in a row it remained at 12.3-12.4v after normal use and there was no loss from evening to morning. Then I started checking weekly, but after a few weeks of seeing consistent readings I lost interest thinking my initial problem was just a fluke as it had not reoccurred.

It's not like I couldn't cough up the cash for the battery, I just want to nail down what the problem is if it is not the battery. Every other car I had where had an issue starting the tests would clearly show it was a bad battery, starter or alternator or I knew I had clearly left something on. This is the first car I've had where I've had two instances of starting issues where there was no sign of a drain and all systems test fine.

KEY08

All modern cars have real issues with batteries that are low on power. This is across the board. I know it sounds like your battery tests fine, but it may be best to just replace it and then see if you end up in the same boat. It is 4 years old and my guess is this is the root of your problems and it is going bye bye on you.

thefisch

yeah I know a replacement is the simplest outcome here that would give me at least a few years of worry free operation. But at this point I am going to ride the wave a little longer since it worked fine for weeks since the last charge and I've got to justify the charger purchase to extend battery life for a bit longer

The jumper cables are now in my trunk just in case. Now once my wife gets stranded with me because of the battery, I am done for . We don't take this car on long trips anyway (wish we did though).

Live Oak

As this thread is smoking, my 2011 E550, 59,000 miles, failed to start this PM. Lights on the dash, a loud click, no crank at all.

No prior slow cranking. No clue anything going on --- that's the surprise.

The car had been driven 10 miles in the AM, typically about 35mph.

Had roadside assistance come jump it. Then I took it on a 15 mile run, mostly 50 mph, in D4 to keep it above 2,200 rpm.

We'll see how it does in the morning.

New battery as soon as I can get one. I'll do Mercedes since they do all my service and I have 15 thousand miles left on extended warranty.

cetialpha5

There are several battery threads out there. I think if you go the Mercedes route it will be around $300, but at Advance Auto, or Autozone, around $140 or so after using some discount codes. Advance even installs it for free. Pepboys also has it for around $150 but they charge extra to install. I'm somewhat surprised that it went, mine is over 7 years old and it's still the original AGM battery. You could probably just take the battery to Advance Auto and they'll put it on a charger for free and it would probably be fine for a while.

porksoda

does anyone know the battery group for the e class?

I have had very good experience with costco batteries with my other vehicles. They are made by same manufacturer as interstate.