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A Lucky Escape today (Flat Battery Woes)..

747 Views 12 Replies 6 Participants Last post by  cowboyt
Greetings all

At 3.30 p.m. today I went to unlock my 2004 W220 (using the Remote control key fob) and nothing happened. Zilch. Locked out. A flat battery in Remote key maybe? :unsure:

So I tried again with the spare key & new battery. Still nothing.:mad: After unlocking the driver’s door mechanically with the detachable ‘blade’ I inserted the key fob into the ignition to start the car. Result: the dashboard display didn’t automatically illuminate as it should, and NO start - just some alarming electrical buzzing noises. Yikes! I’d only ever had a ‘Low Battery’ warning on the dashboard display once, briefly, and several months ago. Nothing since..:unsure:

Then.. I tried to unlock the boot / trunk (again using the mechanical blade key to over-ride the PSE system). Result: much clicking noise from the PSE pump and the Bl**y Alarm went off :eek:. W220s are notoriously complex electrically, and a flat battery could be due to a myriad of other issues. Double Yikes!

So I called my Motor Insurer’s Breakdown & Recovery service for a ‘Home Visit’ (quoted time 90 mins - but thankfully the local agent arrived within 45 mins). After various checks, the technician diagnosed a ‘failing’ 6-year-old battery, gave it a brief Booster charge and confirmed that the Alternator was working ok. His advice: ‘It will start now, get it booked-in for a new battery - but DON’T switch the engine off in between or you’ll be stranded again!’.

By now it was 4.30 p.m. and getting dark: so I drove in trepidation to my friendly & helpful local National Tyres & Auto Care centre 10 minutes away in the hope that I would get there without breaking down en-route AND they would have a replacement battery.🤞 If not, national auto accessory retailer Halfords (known as ‘Halfrauds’ here in the UK) were nearby & open until 8.00 p.m. so I decided to take my chances on either or both to keep mobile and avoid further hassle (breaking down / further Recovery services / Taxi fares etc).

15 mins later, NT&AC had a new OE spec 019 battery in stock and fitted it for £140 all-in. This was exactly the same price as the one I’d had fitted 6 years & 40k miles ago. Their conclusion: ‘pretty good performance for a battery - but the latest UK Cold Snap + increasingly frequent use of ancillaries (headlights, wipers etc) have ‘finished it off’.

End-to-end from the start of my flat battery issue to resolving it took only 2 hours and with no further complications or hassle. All I can say is a big ‘PHEWWW!’

My Conclusion? At this time of year (e.g. in the UK), keep a Close Eye on the health & performance of your car's battery - especially if it's getting older AND with greater demands on it during cold & dark Winter months. Replacing it as a precaution now / sooner could save you more than its cost in terms of wasted time & hassle if / when it lets you down completely.. sometime later? ;)

MB :cool:

'The Best or Nothing'
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· Moderator
2000 S430, 2000 S500, 2003 S600 TT, 2005 E320 CDI, 2006 S500 4Matic, and 2006 S350
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That's true. Six years is about right for a car battery. I've seen recommendations for replacing them every five years for just this reason.
 

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2009 E350 4M Avant Garde, My Mistress 2002 S600, Wife 2014 C300 4M Avant Garde with AMG
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Check your manual: if an AMG battery is specified, it will cost more, but last forever!
On my cars the AMG batteries have lasted 10 years plus.
 

· Registered
Mercedes W220 S320 cdi 2004
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Discussion Starter · #4 ·
Check your manual: if an AMG battery is specified, it will cost more, but last forever!
On my cars the AMG batteries have lasted 10 years plus.
Thanks Kraut56 (y). I agree, but as I needed to use the car the same day (and late into the evening..) I opted for the quickest / 'optimum' solution immediately to keep it / me mobile for some important business.

But yes: I HAVE read that AMG / Mercedes OEM spec batteries are the Best, if a little more expensive. So I'll keep this in mind for next time. The battery I bought has a 5-year guarantee, so not too soon I hope!

Many thanks & best wishes from the UK 🤝
 

· Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG. 2011 BMW 335d
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He means AGM, not AMG. Although with the latest hybrid AMG's, I wouldn't be surprised if the battery is AMG'fied too.
 

· Registered
2009 E350 4M Avant Garde, My Mistress 2002 S600, Wife 2014 C300 4M Avant Garde with AMG
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Sorry about the misspell!
OGM / MB = Varta, Bosch etc. Group 49 for these cars is $ 500.00 plus.
The alternator charge is profiled for a higher voltage/charge on the car software.
 

· Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG. 2011 BMW 335d
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Technically speaking, W220, for all of its advancement and technology, is now 20+ year old. The charging system on those cars are old school....that is, you start car, alternator charges the battery to 14v and stays there for as long as the car is running. The only efficiency that I can think they added at the factory was to install a overrun pulley on the alternator, so less parasitic drag at high rpm, which translates to slightly better mpg. Something like 1-3%.

AGM on W220 is sorta semi-wasted, semi-useful. Given the amount of power draw all the modules in the car have, a AGM battery can supply more amps and tolerate battery drain a lot more than regular lead-acid battery. It does have characteristics, along with the battery location (trunk) which make it last far longer than traditional lead-acid batteries. 10+ years is not uncommon. I personally have seen factory original AGM in R230 and W220 that were over 18+ year old.

Mind you, climate plays a huge factor. Here in LA the temp swing is maybe 60F at the worst (15-16C) from hottest to coldest, so very mild climate in comparison.

However, AGM is also wasted on W220, primarily because modern cars now have intelligent charging and require AGM for maximum functionality. Nowadays modern cars -- at least when it comes to battery charging -- are more like hybrid cars, or even more like your cellphone or laptop. The computer actively monitor the battery charge (called State of Charge, SoC) and intelligently charge when necessary. So when you start the car and idle and the battery is fully charged, the computer will not charge the battery. That is to say, car is running purely off the battery. Saves gas. You drive, still on battery power. When you take off foot from gas pedal and coast, or hit the brakes to come to a stop, that's when the computer kicks in the alternator and charges the battery. They always maintain the SoC between 30-80%.

This is important because AGM batteries can tolerate being discharged all the way to 30% or 20% then recharged back to 80%, then drained to 30%, rinse and repeat. Regular lead-acid can't tolerate this as much. Drain them once or twice, they permanently lose capacity. Do it some more, and over time the battery dies due to increased capacity loss.

W220 has none of those fancy-ass technology. It's the last of the old school tech. So that's why I say AGM, while very helpful, is wasted on it. Plus given the price difference between AGM and lead-acid....$500 vs $200, and it becomes a no brainer.

AGM made sense years ago when the price difference between the two were less than $50. Shame those days are over now.
 

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There is one more factor that has not been mentioned. AGM battery does not contain liquid electrolyte. In case of major wreck with vehicle going turtle there are no spills.
 

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2000 S430, 2000 S500, 2003 S600 TT, 2005 E320 CDI, 2006 S500 4Matic, and 2006 S350
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For the S600 V12, I've found that the AGM battery is helpful. This is primarily because of the slightly increased voltage, about 12.7 to 12.8V vs. the 12.3 to 12.4V for a standard lead-acid battery. The voltage transformer in particular seems to prefer the slightly higher voltage, because it's easier to step up to (I believe) the 180VDC that gets sent to the ignition coil assemblies. The lower the voltage, the harder that voltage transformer has to work, apparently much like the Ford 6.0L Power Stroke Diesel's Fuel Injector Control Module (FICM), and the sooner that components will fail.

For the V8's, though, I don't see much, if any, benefit by using an AGM battery. Costco has reasonably priced AGM batteries, close to the same price as standard lead-acid, so I'll use those when available. Otherwise, I'll use a standard lead-acid battery in an M112/M113-equipped W220. So far, it's been just fine.
 
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