My car is now in an extended warranty period, so the initial 3 year has expired. I still had my battery replaced under warranty 👍

 

I’m guessing your extended warranty is more prescriptive than the laissez faire approach of the MB warranty where it depends on the luck of the day.

 

I’m guessing your extended warranty is more prescriptive than the laissez faire approach of the MB warranty where it depends

The warranty was the 2 year AMG one that is applied to any approved used AMG vehicle. Still have another year left to run. By the sounds of it, I was lucky then?!?

 

The M-B Extended Warranty (which you purchase, as opposed to the one that comes with M-B Approved Used cars) - does not cover batteries.

It also seems to exclude "Lamp Units" - so if your LED Multibeam lamp unit goes, that will be expensive!


Full listing of exclusions in the policy book:

https://assets.website-files.com/602c5a868b23fd8f71d9fd07/608a7b5bdcd05e5bcb8ea098_mercedes-benz-warranty-handbook.pdf

 

Looks as though someone got over generous with the warranty 😁

 

My battery lasted 3 1/2 years and was replaced under warranty. I think I was lucky though, worth a try. I played on constantly getting battery critical message and let them come to the conclusion that the battery was the issue. Rather then telling them the battery was duff.

 

Thanks. Didu contact MB dealer, or online ?
I can call them, but my dealership in Bromley just got sold on So closed till end of March.

 

I booked mine in to the local MB dealer. Got the usual “do you agree to pay the £160 diagnostic fee if no issue found”? That in itself annoys me, but I agreed and they found the battery to be faulty and replaced it. Good luck with yours. Mines back in on Monday for its alarm sounding issue. This will be the fourth visit to have the overhead console, diagnosed and found to be faulty, replaced. They managed to order the wrong part last time. Absolutely hopeless MB Leeds.

 

Well......I booked it in, and got the standard "theres a £174.00 charge for the first hour" inflation rate. Dropped the car off and complained about the stop start function, and the app showing partially charged after even a long (120mile journey). Was told they will keep it overmnight, charge it and see whats what. 4 hours later they called and said its ready. They replaced the starter battery and cleared faults. No mention oif what the faults were, and all I could get was the voltage was low. ~Battery is A 001 982 81 08 - 02/23 . Is that the right one?

App now shows CHARGED, which I would expect.

So thanks for the tip, and anyone with similar issues should do likewise. Since there was not even a question about my low mileage, I suspect there is an issue and thats why no questions asked, battery changed under warranty.

And no "diagnostic fee" either, although they did take it for a 10 mile "test run" which I complained about.

 

So my partially charged battery issue is now resolved after I was stuck in a horrible traffic last week and I was just literally idling for 30min straight in drive (not park). Idk if the gear selection makes a difference but it seems that none of different combinations of driving including coasting, cruising, pulse and glide and WOT helped charge the battery. I drive about 70% city 30% highway.

It also leads me to believe that the dash charge indicator is total BS. It seems idling is best for charging the battery, especially in gear. Also I turn off the engine start stop function for short trips. My battery is always indicated as charged now in my mercedes me app, and if it shows partial I just idle the car in gear until it's charged.

So in my experience, long idling times help to charge the battery, and avoiding engine start stop functionality for short trips help retain the charge.

 

Good result. Pleased you got it replaced with not to much hassle 👍

 

need replacement every two and a half years is ridiculous, especially when it continues to start perfectly happily.

Yes agreed. You’re not the first to make this observation.



People have noticed that car batteries aren’t lasting as long as they used to. - Inland Empire Autobody & Paint Inc.

It’s True: Car Battery Life Is Shorter | Badell''s Collision


A bit like tyres….. I remember in previous cars changing tyres around the 30k miles mark.

These days, I’m lucky if I get 12k miles out of mine (admittedly the car performance has increased).

 

The only bit I agree with in those links is the parasitic drain. When I stopped using my MGB V8 as a daily driver I had to fit a battery cut-off switch as with just occasional uses it would fail to start after a few months.

'More electronic demanding more power' doesn't wash as the alternator is powering all the items listed while the engine is running.

'Smaller dimensions' is incorrect as from what I can see the A-Class battery is more than twice the physical size of the one in my V8 with more than twice the cranking power, and AGM as opposed to conventional lead-acid.

'Less expensive' is ridiculous with the A-Class costing around 50% more and only a 3-year warranty as opposed to a 5-year, from the same supplier.

'Extreme temperatures' is not relevant with both cars in the same country.

Batteries have been 'low maintenance' for decades in the classic world as well as modern.

'Charging weekly' - who is going to do that? I have lithium jump pack, and when I come to need that for the A-Class then I'll put the Ctek on it.

It boils down to #48 with people asking why Start/Stop no longer works, and being sold a new battery when there is years of life left in the 'old' one. It seems to me that Start/stop is inhibited way too early for us in the UK, probably less so for Scandinavian winters and the like.

Tyre life is down to how they are driven as always, and the increasing weight of modern ICE cars let alone electric, I'm not aware of reducing life on my classics.

 

'More electronic demanding more power' doesn't wash as the alternator is powering all the items listed while the engine is running.

Your MGB has EPAS, heated seats, LCD display screens, MBUX and the same amount of electrical ancillaries as a fully loaded A-Class?

Your average A-Class has over 50 control modules all requiring power!

One design change in recent times, is that the alternator is no longer necessarily sized to power all the electrical loads needed by the car AND charge the battery at all times. On many cars, we have frequent scenarios (by design intent) where we get a negative power balance occurring ie; loads are supplied from the battery rather than the alternator when the engine is running.

This is the largest design change in modern production cars - plus the so called smart charging not to 100% under certain conditions.

It boils down to #48 with people asking why Start/Stop no longer works, and being sold a new battery when there is years of life left in the 'old' one.

Yes, there are years of life left purely as a cranking battery. However the SOH is reduced to under 60% after 2.5/3 years, and this reduced capacity is insufficient to run everything at all times.

It’s no good trying to keep comparing with cars of old - things have moved on, not necessarily for the better in pure engineering terms, but always due to additional constraints, and modern cars always have more features and functionality. Those rose tinted glasses always look great

 

"Your MGB has EPAS, heated seats, LCD display screens, MBUX and the same amount of electrical ancillaries as a fully loaded A-Class?"

None of those things are powered with the car parked with the exception of external communication.

"One design change in recent times, is that the alternator is no longer necessarily sized to power all the electrical loads needed by the car AND charge the battery at all times. "

Really? Is that the case on the A-Class? Then as I've said before it's not fit for purpose. And if it were true you would see it from the battery voltage display on the MBUX falling below 12v while the engine was running. Not to be confused with so-called 'smart' charging which should only reduce alternator output when the battery is fully charged, but still keep a positive charge.

 

None of those things are powered with the car parked with the exception of external communication.

I was referring to your earlier comment “'More electronic demanding more power' doesn't wash as the alternator is powering all the items listed while the engine is running.” - so when comparing an older car vs newer car, there are far more electrical loads to consider while the engine is running, and no, the alternator isn’t always sized to cope with the demand.

Also re your earlier comment about AGM batteries, yes you get more CCA because of lower internal resistance, but it’s downside is that AGM is very sensitive to overcharging and will degrade quicker than traditional flooded plates….. hence why in many cases will lead to shorter battery life!

(Use of an intelligent multi stage charger eg CTEK is always recommended for AGM).


Anyway. What I’m suggesting is that direct comparisons of “batteries last over 10 years in my classic cars” is perhaps over simplistic when you’re not really comparing apples with apples.

 

"the alternator isn’t always sized to cope with the demand. "

Like I asked does this apply to the A-Class? Have you tested for that? Easy enough with the on-board voltmeter. I've had headlights, rear fog light, brake lights, hazards (not that LED lighting creates much load) all on, heated rear screen on, blower on full, heated seats on full, all four windows going up and down together and the system voltage dropped from 14.7v to 14.6v at idle. Turning the wheel reduced that by a further half of a tenth of a volt. I've compared the MBUX voltmeter with one directly on the battery terminals and the two were never more than a tenth of a volt different. This ability to maintain near full charging voltage with everything turned on was the same on the Golf 7, a 1990s MG and a 1980s Toyota. Even my 1970s MGBs will maintain a positive charge with all factory loads turned on albeit dropping closer to 12v as they only have 30-40 amp alternators as opposed to 140 amps being common today. You have to go back to dynamo-equipped cars before factory loads will start putting a drain on the battery at idle, and even they charge at normal driving speeds.

If the alternator isn't 'sized to cope with the demand' then you could well be discharging your battery while driving - as I said not fit for purpose.

If the system is over charging the battery then there is a fault.

 

Like I asked does this apply to the A-Class? Have you tested for that?

Yes, on the AMG models, and you get a negative energy balance (measured using M-B Xentry tools - I've also said in another thread that just looking at voltages is not a great measure, as the energy management module is also regulating current flow in either direction)

On another (German) marque, I've seen the back-room customer complaints of cars sat in 4 hour traffic jams in Japan (not uncommon), in rain and darkness where the engines have cut out.

Easy enough with the on-board voltmeter.

I've said previously in another thread - don't alway trust the instrumentation and read out's on the instrument cluster. The voltmeter may be fine, but other readings aren't true sensor readings. eg: the green "charge" section of the dial, or on the AMG models, the HP and Nm readouts are calcualted/simulated/tabulated figures, not sensor derived figures.

Coincidently (!) the AMG cars don't have the on-board voltmeter read out..... they probably thought it would panic the customers too much....

as I said not fit for purpose.

In whose eyes? In the manufacturers eyes, fit for meeting their environmental targets! 😂


I'm not sure what the disagreement here regarding start/stop is. If the battery SOH is less than around 60%, the system will inhibit S/S. The battery has therefore 'degraded', it may well be fine to keep cranking the car (benefit of AGM, higher CCA due to lower internal resistance) - but the battery is considered 'degraded'.



(This extraneous battery posts will be merged into the other battery thread in time)

 

If the voltage is staying at 14v+ then the alternator is carrying all the load, simples.

 

On the whole, yes (there are exceptions for charging in an energy managed system) - but In the case of a non-managed traditional alternator, 100% yes.

 

Hi all, I have an a35 amg 2019 and I changed the battery over the weekend, once completed I noticed that it’s automatically set my dash to default meaning at the moment my dash is in classic, going through the menu I can see that I have sport and super sport. I set my dash back to super sport but that activates sport with lots of warning symbols such as abs, park brake light and hazards start flashing ( only when activating super sport) it’s absolutely fine in classic or sport. Any ideas ???

 

I change the battery last week still "good" the OEM was a VARTA with 69% SOH and 98% SOC but in the app always say: parcialy charged.

So i changed the battery and all perfect didnt have any problems before but for 140$ easy thing to do. and the most important provably is put the SAM on 0Ah to start with the new battery.

 

The MB battery is something like £400. Is that correct.

I was getting the partly charged sign too but in the warm/hot weather it's completely transformed and behaves like new. The start/stop works from the start etc. So we'll see how winter goes.

 

I disabled Start&Stop with CODING and i bought a Hankook Battery 80Ah/800A (same as OEM) for: £121 and i change it myself. And how i said have to use xentry to put 0 the SAM o IBC (the sensor of battery life the one is sending the power (alternator to battery) for charge.

 

Just got my battery replaced.

Any idea how long does it takes to get the new battery fully charge up?

 

It should come virtually fully charged from a reputable supplier, they are supposed to periodically check the voltage and give them a charge if needed. Certainly enough charge to start the engine and drive off, although Auto Start/Stop may take a while to start working. With how some here say 'smart' charging works and with the car crying 'wolf' at the drop of a hat saying the battery is 'discharged' or 'critical' it may take some time for the car to fully charge it depending on usage. Mine's been giving warnings due to low usage for virtually the whole time I've had it but never failed to start.

 

I too would have thought it would have come fully charged too. Certainly back in the day when I did my on diy on the various old bangers I had they did. But in any case a good run should sort out any charge deficit.

 

I need to change my battery, I have an A class 180d late 2018 and I am wondering what battery should I buy, preferably original MB thanks!

 

Look at the existing label on your existing battery?

Eg see the photo in post #4 in this thread.

 

Hi All , looks though my main battery needs replacing. Is this something I can do myself? Will the car need any computer resetting afterwards?
many thanks…

 

See post #1 to #15 in this thread.

 

How old is the 12v battery?

If it is 2020 as in the first post. That seems to be the sweet spot for our batteries playing up. Mine being a 2020 model is still showing partially charged on the app, even after using a charger and going on a 50+ miles motorway run.

Out of interest anyone know what MB will charge to replace it. Around £480?

 

DIY the cost should be about ~£150

Having lifted the cover and charged the battery I am sure I could change it as I used to before getting MBs. But how do you do the coding?

 

Even though I've charged my battery twice and done more miles than usual on the motorway, and even more due before Christmas, I cannot get the partially charged sign on the MMe app to go off and hence the start/stop won't work.

Anyway I found the Varta battery MB use for the A45s on Amazon, £190.02. I also called my local MB garage and they went away and came back with the MB battery price, £420 fitted. I said to them about the Amazon price and they said they will price match it. But £175 fitting and coding on top. So quite a drop overall and I have asked them to note all the details down for when I book my car in for its service and MOT in Feb/Mar.

I have to say I had never heard of MB doing a price match before. But worth remembering.

 

more miles than usual on the motorway

Unfortunately steady state driving on the motorway does not invoke the final 20% charging from the “smart alternator”. The best pattern of driving is one that involves over-run and braking.

Steady state motorway driving only tends to charge the battery up to 80% of the SOH, and it does sound that your battery SOH is down anyway.

More:

https://www.aclassclub.co.uk/posts/203119/

 

The best pattern of driving is one that involves over-run and braking.

I have said that to my wife but she won't buy it 🤷‍♂️