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This is a follow up on a post from a few months ago where clb0099 and I, and others were discussing an alternative to the MB starter batt under the hood. I had been through two in 7 years and had looked for something other than the recommended replacement.
Original is group V4 and a workable replacement is group 47. Somewhere on the net, someone suggested group 49; which IMO won’t fit w/o changing the stock cables-- it's almost 6 inches longer than the stock batt…
Oreilly’s has the V4 and 47. Also IMO, the Oreilly V4 is the Same batt the dealers sells… Here's the spec’s for V4 and 47.
Mercedes V4 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
Group size 47 at Oreilly’s: $230
Group Size (BCI): 47
UPC: # 83996032859
Battery Type: AGM
Height (in): 7-1/2 Inch
Length (in): 9-9/16 Inch
Width (in): 6-7/8 Inch
Terminal Type: Top Post
Weight (Lbs): 39 Lbs.
Voltage (V): 12 Volt
Cold Cranking Amps (CCA): 600 CCA
Cranking Amps (CA): 690 CA
Reserve Capacity (min): 100 Minute
Positive Terminal Location: Bottom Right
Flush Manifold Vent Cover: Yes
Group Size (DIN): H5
I chose Oreilly’s most expensive $230 group 47 , the black one, for a few reasons-- you can probably get a crap Walmart batt for $100--:
1) it fits!;
2) it's AGM, like the Mercedes batt,-- Absorbed Glass Mat-- supposed to be better;
3) Oreilly's will ship this AGM batt for free-- you have to return the old batt to the store for the $22 core charge--;
4) you can find the group 47 in stock anywhere-- V4 is probably a special order-- and;
5) IT'S Bigger!
Yes, by volume, it’s 60% larger than the V4. This is my third starter batt replacement in 7 years. Twice, the V4 batt has left me stranded with no indicia-- like slow cranking—that the batt was failing. I, rightfully or wrongfully, attribute that to the small size of the V4 batt when being called to start my 12 cylinders… I know the MB starter batt is only used for “starting", and there's a big batt in the boot for everything else-- that I’ve never even seen-- , but it seems to me a 60% bigger batt is less likely to leave you stranded… or, at least, give you a clue that it’s in need of a replacement...
And, IT FITS (hence, I can say "Verified")…. The next bolt hole at the bottom bracket is "just right" for the AGM group 47:
That's the "hold down" anchoring the batt at the bottom in the batt compartment...
And the stock cables, although close to the limit for the (+) cable, work too… Verified!
Only, the top bracket (circled in yellow) won’t work-- BTW, it wouldn't fit my V4 batt (both Oreilly’s and MB) either, and had to be zip-tied at the rear… At 2 inches taller for the group 47, I forwent the top bracket altogether this time... The bottom bracket should suffice, even in a rollover…. The outside venting tube (right of pic) fits as well…
And for completeness, the red arrow terminal in the pic charges the boot batt; and the green arrow charges the starter batt, so you have to charge both... Took me over 7 years to figure that one out... LOL... maybe I wouldn't have been through 3 starter batt's if I had known that!!! I religiously had charged the boot batt-- which Could be the one that came from the factory!!!
I kept getting confused about the batteries for my car (2007 S550) and between your post and the explainer article on the other forum, I was able to just pick up a 47 and install it myself, avoiding the stealership altogether.
Weize has the boot batt, Group 49 H8, AGM, free shipping and no core charge for about $150 (you can get a $10 gift card for the old batt at O'Reilly or Autozone). I just replaced my 17 year old MB boot batt with one, and the Weize specs look great.
My starter battery (a 5 year old group 4 die hard from advance auto) went out last night. After reading your post I decided to get a group 47 battery (agm $179) from walmart. It installed perfectly and is a much better battery for $50 less and better warranty. I did not have the bottom mounting bracket so I went to autozone and picked up a universal mounting kit ($9) and got a 1.25 pitch inch m8×1.5" bolt for the existing hole in the battery pan. I snipped the plastic zip tie holding the wires in front of the battery to relieve stress on one of the wires.
Thanks for posting your solution!
Last edited by litespeedone; Sep 10, 2025 at 03:25 PM.
To the surprise of many, electrons inhabiting American made batteries are sufficiently similar to their cousins inhabiting German made batteries that most electrical systems in the car continue to function. The vent tube on the battery is there to allow the residual German electrons, who do not wish to participate any longer with minority status, a convenient means of exiting.
To the surprise of many, electrons inhabiting American made batteries are sufficiently similar to their cousins inhabiting German made batteries that most electrical systems in the car continue to function. The vent tube on the battery is there to allow the residual German electrons, who do not wish to participate any longer with minority status, a convenient means of exiting.
That's a funny way to put it. For a real answer: the vent tube is actually just for battery gases, not electrons. All electrons are identical.
This is a follow up on a post from a few months ago where clb0099 and I, and others were discussing an alternative to the MB starter batt under the hood.
Hello. What is your take on the Energizer brand AGM battery from Costco, which their battery fitment tool recommends for this car?
Old thread, but here's an update. Finally, after almost 19 years, my original starter battery has died on my 2007 S550 4Matic.Just purchased a replacement V4 battery from Advance Auto Parts. It's a Die Hard Gold. Price was 234.99 plus $22.00 refundable core charge. Dealer wanted $288.20.
whilst I put far bigger one in - I don't think there is any point.
the OEM small starter battery (on early twin battery cars) should easily make 15 to 18 years - it does almost nothing in life and the charging system manages to keep it happy - the ONLY thing is its not sealed and like all batteries the electrolyte evaporates off with time - particularly on the outer most two - so by 12 years it will be trying to run the cell next to the positive terminal in air (which is a killer for all batteries) ignore the lying label and top it up - that should see you with another 5 years of no maint and no issues
I guess where its hotter or you cause it to work harder check the level and top up more often
the other thing to bear in mind is the world changed - just about every battery is now designed not to make it past year 5- with the vast majority going south from year 3 - brands, spec, reputation and cost are no longer anything to do with it - we are in the final phase of steal the money before the big ending.... they have known this for many many years its only the lemmings clinging on to a dream there's a happy ending
that's why today's cars and all products are so sort lived and unreliable - you wont need anything where you are going.....
Currently I drive: 2007 S550, 2009 ML350 and 2004 CLK320.
My non-OEM starter battery just died after 6.5 years and some 22K miles driven. Is was standard flooded V4 AutoCraft Gold from Advanced Auto Parts. It was regularly trickle-charged. The liquid level is up the the specs. It just died. I'm glad that this topic is discussed here. I plan on going the H5 (47) route. The only dilemma is to go AGM of stick with flooded. My local Costco has both in stock. What do you think?
My non-OEM starter battery just died after 6.5 years and some 22K miles driven. Is was standard flooded V4 AutoCraft Gold from Advanced Auto Parts. It was regularly trickle-charged. The liquid level is up the the specs. It just died. I'm glad that this topic is discussed here. I plan on going the H5 (47) route. The only dilemma is to go AGM of stick with flooded. My local Costco has both in stock. What do you think?
Stick to AGM. I got an Exide EK720 (72Ah) which fits and gets anchored at the bottom but not the top similar to the OP’s experience. I am on the lookout for a bracket with long prongs pre facelift where the elec distribution unit sits to side of the battery rather than the front.
MB own batteries aren’t that expensive compared to what others are paying, worth checking as dealers seldom run discounts on available stock.
Currently I drive: 2007 S550, 2009 ML350 and 2004 CLK320.
Originally Posted by mcypert
Here's another tip:
Weize has the boot batt, Group 49 H8, AGM, free shipping and no core charge for about $150 (you can get a $10 gift card for the old batt at O'Reilly or Autozone). I just replaced my 17 year old MB boot batt with one, and the Weize specs look great.
Regards... Mark
Mark, how is that Weize battery doing? Do you have any complaints? Please update us.
I just checked this post to see the batt type. I haven't driven the Merc in a while (putting off tackling an AC compressor R & R). Well, tonight, the boot batt was dead. So, can't give the Weize batt a full-throated endorsement, I'll charge overnight and see...
Does the W221 BMS require informing that the battery has been replaced so that the charge management is reset to enable it to correctly maintain the new battery rather than charging to the degraded level of an older battery🤔
So, I charged the Weize boot batt overnight, and it seems to be okay. Best I can calculate, the batt's were 25 days without a charge or car started. The starter batt was fine, so the consumer batt must have some parasitic draw. This has happened a coupe of times before both with the old MB boot batt and the Weise AGM, but only when I let the car sit for a prolonged time. I've never found anything to account for the draw down, but "who knows what evil lurks in the hearts of the MB two batt system." BTW, in case you missed it in another post, the starter batt will charge the essentials to start the car with a dead boot batt, but not vice versa (you can't start with a dead starter batt).
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