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Dead / weak battery ... again?

This is a discussion on Dead / weak battery ... again? within the CLA Problems/Issues/Complaints forums, part of the Mercedes-Benz CLA Forum category; Well like several of us, I have bumped into the car-won't-start days ... though both times it was at a gas station (thank goodness) Last ...

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    jmc
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    Dead / weak battery ... again?

    Well like several of us, I have bumped into the car-won't-start days ... though both times it was at a gas station (thank goodness)
    Last time was 02/12/16 so the battery was 24 months old (since it was put in)
    This time was yesterday 04/05/18 and was 26 months old (since it was replaced feb2016)
    Interesting since 2017 their battery sales warranty is 24 months (hmmm???) ... of course oem new car one is still 48mo
    Anyway this time I managed to capture the data of a "dying" battery ... covers start-drive-stop-slowdeath-restartfail
    (the 2 dips during the dying phase are normal part of the fuel system purging etc)

    Name:  Benz_CLABatteryCondition_040518.jpg
Views: 140
Size:  108.3 KB

    Good grief !! 8-)

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    Veteran saxonjackson's Avatar
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    Quote Originally Posted by jmc View Post
    Well like several of us, I have bumped into the car-won't-start days ... though both times it was at a gas station (thank goodness)
    Last time was 02/12/16 so the battery was 24 months old (since it was put in)
    This time was yesterday 04/05/18 and was 26 months old (since it was replaced feb2016)
    Interesting since 2017 their battery sales warranty is 24 months (hmmm???) ... of course oem new car one is still 48mo
    Anyway this time I managed to capture the data of a "dying" battery ... covers start-drive-stop-slowdeath-restartfail
    (the 2 dips during the dying phase are normal part of the fuel system purging etc)

    Name:  Benz_CLABatteryCondition_040518.jpg
Views: 140
Size:  108.3 KB

    Good grief !! 8-)
    Ohh man sorry that’s not fun at all


    Sent from my iPhone using Tapatalk

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    Must be some drain somewhere. Buy yourself a trusty CTEK charger. My original battery lasted 2.5 years. My warranty-replaced battery is almost 24 months old now, hooked on a weekly basis on a CTEK 4.3MUS. I use the engine start/stop a lot especially winter time so it does take a big toll on the battery.

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    @jmc , only 2 years old... something's leeching?
    I'm still on my original battery. If I know I won't be using the car for more that 3-days I connect my Schumacher 2AMP charger. Never failed me so far.
    Last edited by Bahn; 04-06-2018 at 08:51 PM.
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    jmc
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    Well folks ... this second battery was born with a ctek43 on its terminals and the final charging state has been consistent - right up till the day it died. Even on its last day all i had to do was fast twist the key and ignition was complete. And the charging feedback loop works as planned. Just may be luck of the draw with factory defects on a plate or something. But there is some good news ... mb will do a goidwill out of warranty by 4 days replacement

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    Newbie levinchan's Avatar
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    the first time of dead battery of my CLA200 was 1.5 years.... and I read elsewhere most peoples with CLA and their battery usually dead around 2 years...

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    Quote Originally Posted by jmc View Post
    Well folks ... this second battery was born with a ctek43 on its terminals and the final charging state has been consistent - right up till the day it died. Even on its last day all i had to do was fast twist the key and ignition was complete. And the charging feedback loop works as planned. Just may be luck of the draw with factory defects on a plate or something. But there is some good news ... mb will do a goidwill out of warranty by 4 days replacement
    That's interesting.. maybe the ctek overcharged and killed it?? Did you have it on standard 14.4v charge? or 14.7v AGM?

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    jmc
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    Quote Originally Posted by levinchan View Post
    the first time of dead battery of my CLA200 was 1.5 years.... and I read elsewhere most peoples with CLA and their battery usually dead around 2 years...
    kinda jives with their new "2 yr" battery warranty! heh

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    Quote Originally Posted by Picard View Post
    That's interesting.. maybe the ctek overcharged and killed it?? Did you have it on standard 14.4v charge? or 14.7v AGM?
    Well undercharging kills the chemistry faster for these Varta AGMs so I use the AGM charge profile and keep an eye on the input power draw, the voltage, and the bubbling ... normal as heck
    And I keep a hawk eye on the OBD voltage dial (after the boost of course!!) and the data plots say all normal as well ... so weird
    I might try something different with this 3rd one ... try for about 50% ctek time when the car is dormant?? Hmmm

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    Well undercharging kills the chemistry faster for these Varta AGMs
    I believe most flat batteries in modern cars are down to inadequate charging, this is due to stop/start and regeneration, with regeneration the EMU will not allow the alternator to charge the battery via engine power if the SOC is above 75%, the other 25% charge must be by regeneration only. This means the battery is mainly undercharged which shortens its life. To test this just disconnect the negative rail battery sensor which will force the EMU to charge the battery continuously as it did prior to smart charging, the charge rate is between 13.8 and 14.3 volts, in this regime the alternator will always attempt to charge the battery to its full extent.

    By doing this, stop/start and regeneration will not function, as far as efficiency is concerned this makes little difference.

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