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Time for new Batteries

Discussion in 'Electrics, Vacuum, Ignition and ECU' started by Tony Dyson, Oct 22, 2019.

  1. Tony Dyson

    Tony Dyson Senior Member

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    God's Country
    Your Mercedes:
    2014 C 220 CDI W204 OM 651
    My main battery has been deteriorating for some time now but only evidenced by proactive self-monitoring, after being parked up for a couple of days I now have a resting voltage of 11.2v but the car still starts immediately on the turn of the key and the Stop/Start function turns green within a couple of miles driving, although it soon runs out of juice and needs to recover more often than it used to. Below is a waveform of this morning’s start indicating the 11.2v resting voltage, the first dip at 5s are the glow plugs with the start initiated about 2s later, this created a battery voltage drop down to 5.6v but soon recovered back to 10.5v after less than a second it took to start the car where around 5s later the Battery Control Module ramped up the charging voltage to a steady 14.5v.

    upload_2019-10-22_12-43-46.png

    Truth is I’ve been expecting the battery to fail completely for a while, but it just keeps on going so I’ve decided to replace it while on a high, rather than run it to destruction as with the weather turning colder the chances are it’s sadly not going to last for much longer, I’ve ordered a couple of batteries from Tayna, a Varta as a direct replacement for the MB branded Varta main battery and an Exide to replace the MB branded FIAMM Aux (Stop/Start) battery, I did try MB Grangemouth for replacements and they were most helpful but unfortunately they couldn’t get anywhere near the Tayna prices.
     
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  2. Wighty

    Wighty Senior Member

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    Your Mercedes:
    W211/E320cdi/2009 and CLK200k 2009
    11.2 is well low buddy , pretty much failed .
     
  3. OP
    Tony Dyson

    Tony Dyson Senior Member

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    I know, it's defying all logic still driving all the electrics and starting the car, and it needs to continue for a few more days now as the replacement turned up this afternoon damaged in transit, so we'll see how long it takes Tayna and DHL to turn that one around? :rolleyes:

    20191022_161854.jpg
     
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  4. Wighty

    Wighty Senior Member

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    That's an irritation ! I reckon first cold morning your car won't start . Fortunately you are on the case :D
     
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  5. AJD

    AJD Senior Member

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    Your Mercedes:
    2012 W204 Sport ///AMG Line 4dr Auto, Obsidian Black, Light Grey Faux Leather. And no AMG badges !!
    That really is the law of sod :rolleyes:
     
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  6. Botus

    Botus Senior Member

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    S500/2010/500
    if its an AMG battery open it up and top it up… give it a charge and magically over the next 6 month it'll improve. In 2 years you'll find it actually works better than the replacement
     
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  7. OP
    Tony Dyson

    Tony Dyson Senior Member

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    Well I think I'll look into recycling my old car batteries as I have a domestic use for them I'll have a looksee what electrolyte is in them? thanks for the suggestion!
     
  8. Botus

    Botus Senior Member

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    if its AGM you'll see the plates open to air !!! and what looks like dry tissue paper
    put about 50ml of distilled water in each cell and leave for 24hrs then check / top up again and leave till its damp no visible water and the plates are covered as the AGM (absorbed glass matting) has started to do its job again - just like the battery will do.

    the 13 year old one I took out 4 years ago is better then the one in there
     
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