So my mechanic is suggesting that I replace my front starter battery. I bought a Duralast battery as it was suggested by a fellow forum member and I picked it up from autozone. It’s still under warranty but it seems that most of the auto zones near me no longer stock it so I am going to end up getting a refund. Can anyone suggest a better battery for the starter?

 

clb0099:

I got my last one at Oreilly's.

Comment: I've been through two of these is the last 5 years. 1st from the dealer at $200+. 2nd at Oreilly's at about the same price as the dealer (Oreilly's has them, 200 clams. I checked... I'll explain below.)

Both times, the starter battery failed without a bang or a whimper... not even a click of the starter or dimming of dash lights. Both times left me stranded because it started fine when cold, but not even a click when starting warm. Last time I even checked the voltage while stranded and it wasn't low (12.5V or so). I was sure the starter had failed... so much so, I called a flatbed! I had jumper cables but didn't even try.

The reason I know Oreilly's still has them is because a third replacement is in my future, I think. Last warm start stopped for a second before it kicked over. Based on past experience, I think that may be all the warning we get... It will start fine cold and leave you stranded at the first stop...

I think my Oreilly's battery is still under warranty, but I'm thinking, Why bother? It's identical to the dealer's but it's $200 plus tax and only 520 CCA (Cold Cranking Amps). I'm sure there are cheaper and higher CCA batteries that will fit in the engine bay battery compartment.

Anyone know of a group size that will fit? (OEM is: Battery Group Size V4 ; Height (in): 5-7/16 Inch ; Length (in): 8-1/8 Inch ; Width (in): 6-7/8 Inch ; Terminal Type: Top Post, right positive).

Finally, the trunk battery, group 49 (the one I've never even seen) has a 900 CCA. I plan to find it and be ready to jump myself, if I don't fit another (better) battery soon. I guessing the starter battery will leave me stranded again, soon...

Regards... Mark

 

Mark,

After doing some research I cam across this article which says that group 65 battery will fit in that area. I have duralast gold and it’s 2 years old and my mechanic is saying that I should replace it. Below is the link. The group 49 battery is for the rear and group 65 for the front starter battery.


https://www.youcanic.com/post/2009-2...ry-replacement

 

I'm not convinced you are having repeated battery failures. It does actually sound like a starter issue based on your description.

 

Thanks Guys:

clb, thanks for the tip on group 65. Here's a comparison:

Mercedes at Oreilly's: $200
Group Size (BCI): V4 35 Ah; Starting Battery; Battery Is Vented To Outside Of Vehicle; Auxiliary AGM Battery Used For The Backup Braking And Computer Systems; Located In Engine Compartment.
Cold Cranking Amps (CCA): 520 CCA
Reserve Capacity (min): 35 Minute
Length (in): 8-1/8 Inch
Width (in): 6-7/8 Inch
Height (in): 5-7/16 Inch

Oreilly's cheapest Group 65: $110
Group Size (BCI): 65
Cold Cranking Amps (CCA): 650 CCA
Cranking Amps (CA): 800 CA
Reserve Capacity (min): 120
Length (in): 12 Inch
Width (in): 7-3/8 Inch
Height (in): 7-5/8 Inch

I need to check the dimensions of the battery box, but I just took a quick look and, at a minimum, the positive cable will need lengthening for a group 65-- But only on the charging side of the cable, not the big cable running straight to the starter. Take a look under the hood of your car and you'll see what I mean.

(BTW, the charging post with the blue arrow in the pic below is used to charge both batteries. It's under the black cover next to the starter battery. The red arrow is the one that will need lengthening for a non-V4 starter battery. All it, red arrow, does is charge the starter battery, I think...)



kevm14, I totally agree with you (that it sounds like a starter issue). That's why I called a flatbed (although I had jumper cables and another perfectly good, and big-***, battery in the boot!).

Only several days after the car was towed back, and pushed in backwards, to my garage, did I try a jump start. In fact, I had been pricing starters and looking at WIS, anticipating a painful starter replacement was in my future. New battery = no problem... for 26 months...

And, I just dug out my battery receipts:

Aug 2016, dealer battery. Two year warranty.

May 2019, Oreilly's battery. Three year warranty on $160 cost = about $40 credit if replaced today...

Hence, my dilemma... Like clb's mechanic, I wondering if, at 26 months, it's time to replace the starter battery. And, do I go OEM or fit a larger, better battery???

And, back to the quirkiness of the MB starter battery... Why did MB eliminate it and go back to the single trunk battery? And, should that 35 Ah (1 amp for 35 hours) battery be starting a V-8, much less a V-12 like I have?

MB did a lot of backflips to isolate the starter battery from the rest of the electrical. But in doing so, did they undersize the this "special", and most crucial, component and place it in the most hostile environment imaginable? Yes, "Engineered like no other!" as they say... They do, however, learn from their mistakes... Mostly... Personally, I kind of like the separate starter battery... But, should it be replaced prophylactically every two years??? How about a poll on starter battery longevity??? I vote for when the warranty is up!!!

Regards... Mark

 

The smaller AGM battery works as a starting battery because that's all it does. The other loads are sustained by the large trunk battery. I think mine is an OEM with a replacement date of 2018...

 

FYI: My OEM starter battery is still starting my 2007 5 years later.

 

CORRECTION (big one):

I incorrectly stated that the terminal with the blue arrow charges both batteries in post #5 and I've said the same thing in other threads on the forum. IT DOES NOT.



I mistakenly assumed (as in ***-u-me) that the DAS instruction to use the starter battery negative post and the "blue arrow" post to connect a charger would charge both the starter and the trunk batteries. The Xentry/DAS instruction w/ a photo comes up every time you start the diagnostic process. In fact, that charging configuration only charges the aux/trunk battery, for those of us that have two batteries.

Kevm14's comments made me think (thank you kevm, "Thinking", always a good thing for me to "try" now and then..). Here's why. I usually only start my V-12 once every 2 weeks or so (it's my "highway" car)... and knowing that is bad for batteries..., I always put a full charge on with an automatic 12A charger at least every 2 weeks. So, for years now, I've only been charging the trunk battery and the starter battery has been left to it's own devices... sometimes for weeks. Kevm made me think, why might that lazy little battery not be keeping up with it's much older big brother?

Being time for a charge, today I hooked up the charger as usual and got out a multimeter. Yup, blue arrow post went to 14V and red arrow post was at about 12.4, i.e., no charge going to the starter battery. Meaning, we need two charging cycles; one for the red arrow post and one for the blue arrow... I checked and charging the red does not charge the blue, and vice versa...

Another interesting factoid: before hooking up the charger, battery voltage was about 12.8 for trunk battery and 12.4 for the starter battery. I've never even seen the trunk battery in over 7 years of ownership... Meaning, to me, I've been a good steward of the trunk battery and totally starving the orphan starter battery-- staring me right in the face every time I think I'm giving it nourishment...

But, back to my quarry on starter battery longevity, EasyPhil and Kevm's anecdotal evidence made me think again about my apparently short-lived battery. (I'm not sure my 26 month old battery is going south, but I'd like more than 12.4 after sitting for two weeks, e.g., I got 12.8 from the trunk, and starting "seemed" weak on a recent warm start.) First, speaking of going south, I live in the tropics and heat is the enemy of car batteries. Second, I've clearly neglected making sure the little battery was kept charged.

That said, I did one more voltmeter test. To check the alternator charging, I measured the voltage after engine start. Strangely, or not, the trunk battery went right to 14V, while the starter battery slowly crept up: 12.6, 12.8, 13.0 and so on. So, it's charging with the alternator is okay but-- to me-- seems to be unequal??? I know the two batteries are isolated from each other, but are they charged at different rates as well??? I'm not really asking, just puzzled???

But, here's a real question. On the last starter battery failure I called a flat bed when all that was needed was a jump. So here's the question: Can I use a single jumper cable from the blue arrow post in the pic to the positive post on the starter battery?

I don't see why not. The wire size running from the big-*** 900+ amp trunk battery is about 4 gauge, while the starter wire is about 6 gauge... In a pinch, you could even short the blue and red in the pic with your lug wrench... Only ask because... remember the flatbed???

I do know this... I'll certainly try it next time before I call a flatbed... And, I seem to recall throwing some code when jumping with another car which, according to my battery records, was in 2016. I cleared it with DAS and had no ill effects. I'd rather have a code than a flatbed...

So, congrats to me... Masters Engineering degree and 7 years of S-class ownership and I finally learned how to charge a battery!!! WTF...

One final shout out to clb0099: Saw in your other thread, group 65 won't fit... Correct? Glad I didn't waste anymore time on that transplant. Anyone else know of a substitute? I still think the V4 is puny and hard to find.

Regards... Mark

 

Mark,

you are correct as the link I attached to my post lead readers into believing that the group 65 battery would fit in place of the group v4 battery. Needless to say that is not true. If you carefully look at the picture in the link you can see the battery compartment is different than our 2007-2009 models. I ended biting the bullet and buying a v4 group diehard battery for $235. The dealership wanted $315 for the oem battery. Being that I already have a brand new diehard battery for the year one I figured I would stay consistent. Unfortunately my mechanic opened up the box for the oem alternator and besides it’s being broken it seems they sent an used one. I am thinking that there was a total mix up from the place he ordered as I ordered from FCP euro at first but he said to get the one directly from the dealership. Anyway the car will be ready for pick up tomorrow and I leave a week from tomorrow to Florida so hopefully the car lasts lol.

 

HA. I also have the same degree but am still under 1 year of S-class ownership (but two years of W211 AMG ownership if that counts for something - similar dual battery situation though they perform totally different functions).

 

And, while I'm on a roll... Here's another CORRECTION (Jeez, I can't get anything right...):

My Oreilly starter battery is 38 months old-- not 26, as I said-- and out of warranty. (That COVID year didn't count, right?) So, the Oreilly V4 outlasted the dealers. And in that regard, I have a gut feeling the V4, no matter where you buy it, comes from the same manufacture, i.e., there's no difference with the MB branded battery. (One exception noted below.) This is partly because they all look identical, but also from hearsay from an Oreilly's battery supplier that made batteries for both Oreilly's and Jaguar dealers. So, it wouldn't surprise me if there is only one manufacturer that supplies all the V4's on the market, dealer and otherwise, e.g. Walmart doesn't sell them because their batteries are crap...

But back to the subject at hand... Thanks to everyone who posted, I took a closer look at my battery situation because of the discussion and I've changed my calculus on the starter battery: 1) my battery is "old"-- 3+ years; 2) because of my misunderstanding of the charging procedure, my starter battery hasn't ever been charged except by my very limited drive time, potentially shortening its life; 3) a group 65 won't fit, and; 4) the V4 is available at some of the chain stores (I only have Walmart, Oreilly's and NAPA near me).

And, about NAPA, here's their recommendation:

Part #: BAT 8496RAAA
Line: NAPA Batteries
$199.99
Reserve Capacity 90 min
Battery Terminal Type SAE
Manufacturer Part Number 696RMF
BCI Group Size BCI No. 96R
Sub Brand Premium
VMRS Code 32001001
Cranking Amperage 740 A
Cold Cranking Amperage 600 A
Wet or Dry Wet
Battery Type Wet
Weight 34 lbs
Brand AAA
Warranty Code 3 Year Free Replacement + Limited Warranty
Length 9.5625 in
Positive Terminal Location Top Right
Amp Hour 55 AH
Voltage 12 V
Manufacturer East Penn Mfg., Co.
Height 6.875 in
SDS Required Yes
Width 6.875 in

Compare that to the V4 spec's in post #5. It has better specs, but: 1) it doesn't say it is AGM “absorbed glass mat”-- which by all accounts is superior to standard; 2) it's physically bigger, and, after taking a look, will fit, but not with OEM clamps, and; 3) it's the same price as Oreilly's-- which for me, are literally in the same parking lot, NAPA and Oreilly's in Port Isabel, Texas.

So, we have Group size 96R. I think it will fit, albeit incorrectly. And, you can get it at Walmart for $100.

My choice, if I indeed do need a new starter battery, will be the Oreilly's V4. Wouldn't it be nice if all W221 issues could be solved with $200???

Regards... Mark

 

Can anyone comment on what happens (if anything) regarding losing memory/settings on the car during a battery swap? I know some people use a 'keep alive' power source plugged in to the OBD during battery changes, to avoid problems. In MB, just unplug and no worries? How about the rear battery?

 

It appears that if you do the rear battery, the front battery maintains everything, though the car will appear to be totally dead when you disconnect the rear battery. And I assume when changing the front battery, there will be no issues since that battery is only for starting anyway.

 

not on mine - early cars with 2 batteries

to disconnect the clock and reset (if you haven't for some reason got the software right yet) and or to disconnect the car's interior electronics (thus making the gatewqay go completely to sleep) you can open the boot, lift the spare wheel cover and you'll find the other end of the rear battery earth wire just beside the spare wheel (on my RHD car its on the right side of the spare wheel well) - remove the 13mm bolt (with red paint on its head) - all the cars electronics inside goes off (did it twice in the last two days to reset my gateway after throwing things in a tail spin !!!)

when you have done this all four windows and the sun roof anti trap needs resetting (wind down and press and hold the up position and maintain for a few seconds after fully closing) - the rest of the car should happily get over itself - with the clock and date auto fixing if you updated the software patch re post April 2019 WNRO bug -

 

What I said certainly applied to my car and I assume early/pre-facelift models. I disconnected the rear (battery water top-off experiment) to remove, but left the starting battery. Car acted completely dead. When I reconnected the battery, I don't think a single thing was reset, including power windows. I assumed when I disconnected the rear battery, the car failsafed to the starting battery just for module memory purposes (but like I said was otherwise totally dead).

 

So I wanted to add this little information that I came across. It looks like the group 47 battery fits in the space of v4 battery. Batteries plus has group 47 battery. Just by eye it definitely seems it will fit and will give you alittle more cca than the oem one. Batteries plus batteries to me have a great warranty. Here is the link for the battery



https://www.batteriesplus.com/produc...iABEgJPTvD_BwE

 

Good to hear, folks, about nothing going haywire with disconnecting the battery/batteries. One more question...I plan to install new Xenon bulbs shortly...anyone know which battery powers those? I'd rather not get a 25,000 volt shock. Maybe unplug both, and let it sit overnight in case there is a charge left in the capacitor? And, yup, I do have the clock fix software installed.

 

how long did you disconnected it ? the clock drops out straight away, the GCW needs 10 to 15 mins,
on mine all I checked goes off, door end lights, boot lid lights, interior lights, alarm sounds (if opened just the boot to get at the battery only), if doors unlocked the alarm stays off

 

A couple hours I would say. It's probably due to pull it out and check the water. The capacity still seems diminished...

 

Group 47/h5 battery will work. I used a $179 walmart agm for my starter battery. It was $50 cheaper, higher amp rating, agm, and better warranty than the advance auto group 4 battery. The group 47 battery is about 2" taller so I ended up not using the top tie diwn but used the bottom mounting from a $9 universal battery mounting kit from autozone and a 1.25 pitch 8mx1.5 inch bolt in the existing battery pan hole. I also snipped the zip tie holding the two battery cables in front of the battery to relieve stress as the group 47 batteryis a little wider.

 

Hi Mark, I learned when installing a brand new battery, to get it home and fully charge it up prior to normal driving usage.

Reading various articles about this and personal experience, the alternator takes along time to get a brand new 1/2 to 2/3 charged battery from the Autozone warehouse, fully charged.

A few articles mentioned to get a new battery from the Autozone warehouse sitting for 3 months to fully charge from the wimpy alternator would take an 8 hour drive on the freeway.

I have a 2009 W221 S600 V12 with the small battery in the dash, no trunk battery.

I drive 4-5 times a week usually more than 15 miles and it always starts strong and runs immediately.

If I go out of town for > 1 week, I hook up the smart trickle charger (turns completely off when fully charged, reducing greatly the water boiling out). When I get home, battery is fully charged, and it functions like I never left.

I try to stay far away from repeated deep cycling as the W221 MB brains go koo koo when voltage gets too low.

I live in Portland, Oregon, considered a moderate temperature zone, park in the garage at home/work, stay away from deep cycling the battery.

My automobile and motorcycle batteries consistently last 5 years. I have changed them out at 5 years proactively.

Please check out Battery University detail knowledge about many types of batteries.

https://batteryuniversity.com/

JR

 

By "front starter battery" you mean the main battery in engine bay, right?

I bought one from Costco. Energizer brand. A hefty beast weighing in at 50+lbs. Was not cheap. The first one died on me in less that a year. But that was mainly my fault. I live in an area where the winters get *extremely* cold. The car was parked in unheated garage for entire winter and not driven. I only started it a few time to heat up the engine oil so any accumulated water vapours woudl evaporate. Did not use a battery maintainer. So I got what I deserved. The battery quietly died early in the spring season. Costco has best 5 years warranty so I got a new one. I now plan to have it hooked up to a battery maintainer throughout winter.

 

While the spec calls for group 4, I went with a group 47 agm battery from walmart because it has a 4yr free replacement warranty and it is an agm, and has more cranking amps and was about $50 cheaper. It is bigger but fits using the lower tie down and taking out the upper tie down.

 

Varta 535106052G412 (AUX1) 35Ah 520A
Varta 535106052K262 35Ah 520A
Varta 535106052I062 35Ah 520A
Mercedes OE A2305410001 35Ah 520A

 

There is so much confusion with this. Earlier w221 have a small starter battery up front (damn thing is about the size of a large motorcycle battery. Think it was a V4 size that somehow I was able to grab at Advance Auto.) Then the big boy in the trunk.