"Faulty" brand-new battery for ML63

Discussion in 'Electronics' started by ab9758, Mar 19, 2017.

  1. ab9758

    ab9758 Member

    Messages:
    57
    Joined:
    Mar 25, 2012
    Location:
    Central London
    Car:
    ML500 (ex-ML63 AMG and ML55)
    AA replaced my flat battery five days ago with (their own brand?) AGM 900amp. Service is great - they come to house and 2 hours later it's all done. (Don't forget driver's seat has to be dealt with to install battery.) Added bonus is that I have AA repair cover so only paid £35 for £300 battery.

    That's the good news. Three days later, dead as a dodo. AA call out and jump lead start, but now fearing it'll let me down again. Have become neurotic and turn off everything I can think of that may stay on overnight (interior sensor, towaway protection, even Comand on/off.)

    The only clues i have are that the Parktronic beepers have never been reliable and turn themselves on and off at will. And secondly, when I got into the 'dead' car there was a very loud alarm sound from the dash that stayed on for 20 minutes. Not a burglar alarm sound, more like the loudest warning imaginable from a car fault.

    The dash and all displays were dead so I couldn't see what the alarm was for.

    Other electrical oddity is the rear entertainment monitors. They started to show TV Error permanently, but after two jump lead starts from flat they came on perfectly. It's as though something reset them. Might see if there is a fuse for them I could play with to recreate function

    Is there a diagnostic to see if anything is sneakily draining the system overnight? AA will check battery if I ask but it means another call out and I would prefer something obvious!

    Alan
     
  2. Submariner1

    Submariner1 Member

    Messages:
    46
    Joined:
    Nov 9, 2016
    Car:
    CL500 5.5L
    Just been through that. I changed my 7 year + old working battery . As it was showing 12.3V on the car, for a brand new Mercedes one. Belt and braces! Ha ha
    The new one arrived showing 12.8V Which is good? But still gave it a 4 hour top up with new CTEK charger ( the most gentle one max 3.7A max voltsge 14.8V.

    Next day it would not start?? Showing 11.2V wtf?
    Called Mobilo, 5 pages of STAR fault codes all low voltage related. 3.5 hours later conclusion the car was perfect, with a very low battery drain of 0.03A. But the battery was faulty and had gone down to 9.7V and the cold crank rating was 59A not the stated 850A!
    They instslled another new one ... all perfect. Left standing 3 days Voltsqge still 12.8V.
    Summary ... It happens! And big V8s really can not tolerate low voltage!
     
  3. OP
    OP
    ab9758

    ab9758 Member

    Messages:
    57
    Joined:
    Mar 25, 2012
    Location:
    Central London
    Car:
    ML500 (ex-ML63 AMG and ML55)
    I'll give it a go for the next two days. (Just ordered a set of heavy duty 1200 amp jump leads on Amazon as there are many neighbours.) Dilemma is I may call AA Battery Service people (a specialist unit) to come back, diagnose and fit another new one. Although latest AA patrolman said don't bother, just get car to Mercedes and for them to fit their own. (I think AA will pay for this under my policy)
     
  4. Bobby Dazzler

    Bobby Dazzler MB Club Veteran

    Messages:
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    Location:
    Mittel England
    Car:
    ML AMG-line Black Series
    Do you have COMAND and is it working as it should? Our COMAND started misbehaving, and eventually caused a drain, with similar symptoms and series of events t what you describe, albeit with Mercedes breakdown assistance rather than AA.
     
  5. grober

    grober MB Club Veteran

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    Location:
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    Perhaps your alternator isn't charging enough? Did the AA guy check its output? Its that or a parasitic drain of some kind, or simply a faulty battery from new -- it happens.
     
  6. Submariner1

    Submariner1 Member

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    46
    Joined:
    Nov 9, 2016
    Car:
    CL500 5.5L
    I seriously would avoid jump starting that car. The big V8 are prone to blowing control units! Very very expensive.

    I think he is trying to tell you something. :-/
    If it were mine it would be straight into a main dealer, nice new MB battery. Even if Inhad to pay formthe recovery and the battery. But then your finances might be a lot better than mine, and can risk damaging those SAMs and control units.
    NB some are placed in difficult = expensive places to get at.
    Sadly I cant afford to be hit by £000s repair bills for the sake of a £150 battery.
     
  7. AndyRan

    AndyRan Hardcore MB Enthusiast

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    Jan 22, 2016
    Location:
    Kent
    Car:
    R129 SL 500
    Sounds more like a battery drain than a faulty battery to me. What voltage is the car actually putting out when running - Ignore what the car is telling you put a multi meter on

    If its a good strong 14v + let the car go to sleep and see if there is a drain pulling current
     
  8. Auto-mobile

    Auto-mobile Hardcore MB Enthusiast

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    Parasitic drain, no computer will tell you what's causing it.
     
  9. Submariner1

    Submariner1 Member

    Messages:
    46
    Joined:
    Nov 9, 2016
    Car:
    CL500 5.5L
    Sensible, but remember to oeave it a good 15-20 mins. With my defective new battery. The extremely undervoltaging stopped a few control units shutting down, and at one point I had 5 pages of undervoltage STAR failures, and a current drain of 8 Amps!! And 9.7 V on a few items with one historically down to
    7.9V!
    Nice new battery, cleared all codes, re ran star, and zero dtc fault codes :):). Battery drain down to 0.030A to 0.010A wgich they say is excellent as it has a tracker unit.
    If the car is left to stand for 2 days unused the voltage reading ( yeah I know you need to disconnect the batter for an accurate reading is 12.8V. )
    Engine running at idle what 700rpm 14.2V at 1,000 rpm 14.8V.
     
  10. Submariner1

    Submariner1 Member

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    46
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    Nov 9, 2016
    Car:
    CL500 5.5L
    True, but cant it at least tell you, that you you have no fault codes, and with that knowledge start pulling fuses till it disapears? Then you know where the drain is?
     
  11. Auto-mobile

    Auto-mobile Hardcore MB Enthusiast

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    Unfortunately somthing staying on when it shouldn't doesn't really show as faulty, you can connect a multimeter, start pulling fuses and still not find the cause, there are a lot of components that are controlled by a control unit and not fused.

    This is when finding a drain becomes a pain.
     
  12. flowrider99

    flowrider99 Hardcore MB Enthusiast

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    Is there any evidence that jump starting causes issues? I have occasionally jump started my car and other peoples and never had an issue.
     
  13. Bobby Dazzler

    Bobby Dazzler MB Club Veteran

    Messages:
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    Joined:
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    Location:
    Mittel England
    Car:
    ML AMG-line Black Series
    Our ML had a battery drain caused by the COMAND unit. Mobilo got the car started and changed the battery. When the car came back to life the reversing camera wouldn't work.

    Mercedes said it was probably caused by having been powered down completely, but whether it was that or something Mobilo did to get it started I don't know, but electronics can be fragile.
     
  14. flowrider99

    flowrider99 Hardcore MB Enthusiast

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    I read similar things where it is never certain what caused the problem and sometimes someone will say it could be due to jump starting the vehicle but having never experienced an issue or known of anyone that has had an issue I just wondered if there was any hard, clear evidence.
     
  15. JDL60

    JDL60 Hardcore MB Enthusiast

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    Not on an MB, happy never needed jumped- on a Volvo V70 T5 I had the ECU fried by a jump start by a sub contractor of Green Flag near Warrington.
    However I must add that the operative in question connected the leads wrong way to start with- I wasn't present with the car or I may have strangled him with them!
    Nett result ECU and reset c£300 bill. Nice
     
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  16. flowrider99

    flowrider99 Hardcore MB Enthusiast

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    This again proves my point, was the issue due to a jump start or because the jump leads were on the wrong way. No one knows for definate.
     
  17. Submariner1

    Submariner1 Member

    Messages:
    46
    Joined:
    Nov 9, 2016
    Car:
    CL500 5.5L
    Like you I've heard lots of warnings but only one person gave me any sort of reasonable answer.
    When I had all that battery trouble, the new but faulty battery wouldnt even get through the Star Initial Test and stopped part way due to low voltage.
    The technician ex MB in house mechanic expained, the the problem was due to Surges and showed on his Van a proper mercedes one a huge anti Surge thing.
    He said without that level of protection he would never let anyone jump hHis Merc.

    When I asked do all the Mobilo subcontractors 'out of hours guys' have the same stuff .. he just said "hmmm I would ask them to low load it to a dealer or back Home"

    That kinda explained how you hear if folks getting away with it.
    Bluntly surges are not good for sensitive electronic components, and although tou might get away with it ... did it do any slight damage
    Who knows ?

    Personally I could always afford a tow. I couldnt afford to replace a ton of control modules .. so I play it safe ... no jumpstarting, unless its the true Mercedes Mobilo or low load it.
     

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