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Alternator or Battery

DCH May 13, 2019

  1. DCH

    DCH Registered User

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    Aye well, thought things were going too well .... serves me right for the inop headlight washers only being a fuse

    Had the car since Sept 18, never used over winter apart from the odd start up to tick things over, been using more this last month but only a day of so a week for half hour runs. Have charged the battery up once in that time when lights were dim and sluggish to start over winter. Today at lunch time short run I got a warning tone and yellow headlight bulb warning, funny no bulbs out. Drove home from work tonight car started as normal, 15 miles and just parking up in garage and another warning tone and red battery warning light which I think is the alternator. Switched it off and tried to restart and it’s dead and very dim instrument panel.

    It’s not my daily so not fussed other than the wallet about to open. I’m guessing the battery needs replaced as minimum, don’t know it’s age but it’s a platinum ? and I think the car sat for a while before I purchased. Hoping it’s not the battery and alternator

    What’s the next clear steps in the process of elimination? I have a multi meter and battery charger.

    Your help appreciated

    DCH
     
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  3. RAF_S7

    RAF_S7 Well-Known Member Gold Supporter

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    How old is the car, and is the battery original to the car?

    I would charge the battery overnight and then install it back in the car.

    Check the battery voltage before you start the car (anything between 12.2 ~ 12.6v is healthy)

    Start the car while measuring the battery voltage (have someone start the car while you measure). Voltage will drop while cranking, but should immediately come back up once stop cranking. Voltage should not drop below about 10.5v. If it does drop lower, chances are goosed battery.

    With car running, measure battery voltage. If alternator is working/charging, you should see around 14.5v.

    See this YT video for more info....

     
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  4. desertstorm

    desertstorm Moderator Staff Member Moderator VCDS Map User

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    Check the battery terminals are tight. When you get the car started , you may need to charge the battery, check the voltage on the battery to see if it's charging ok. If you haven't got at least 13.8V then it's likely the alternator is faulty. Quite often the alternator regulator is faulty usually caused by wear on the brushes.

    https://www.ebay.co.uk/itm/Alternat...6-Bosch-Top-Quality-Replacement/232413854792?
     
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  5. Maz

    Maz Moon is made of green cheese

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    I went down the route of trying to replace the regulator first a few weeks ago when I had a similar issue but that didn't solve the problem.

    Had to buy a new alternator but still have the nearly new (tried once) Bosch Regulator if you're interested.
     
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  6. DCH

    DCH Registered User

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    The battery that’s in, I’ve noticed the cables secure over the battery posts, but you cant get them tight tight. I did think this might be an issue. It’s been charging up overnight and I’ll leave it on today and go through those checks tonight.
    Thanks for the replies RAF and Desertstorm. If it turns out the Alternater, how easy are they to change in the S3 8l and I’m guessing there will be a how to in here somewhere?

    DCH
     
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  7. DCH

    DCH Registered User

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    I’ll see what tonight shows Maz, thanks

    DCH
     
  8. Maz

    Maz Moon is made of green cheese

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    No worries.

    It's easy enough to change but very tight in there... Lots of guides available to help. The hardest part was lifting the damn thing out of the bay.
     
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  9. DCH

    DCH Registered User

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    Battery charged to 12.65v
    Started 12.15v
    All electrics on 11.7

    Guess that’s the alternator then, and batteries healthy right?

    So next question, new or second hand mofo

    DCH
     
  10. S3AMJ

    S3AMJ OEM+

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    What price are you looking at for a new unit mate? Buying secondhand is always a shot in the dark when you don’t know your source. If a new one is to much, maybe look at reconditioned from a reputable company that’ll give you some warranty.
     
  11. DCH

    DCH Registered User

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    Bosch £200-£280 im seeing... what’s with that surcharge with ECP... is that for exchanging your unit?

    I’m thinking of going second hand on a breaker and hopefully it’s been a replacement at some point in its life

    DCH
     
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  13. S3AMJ

    S3AMJ OEM+

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    Yeah usually if they quote surcharge it’s in exchange of your old unit. A lot of companies will do that now because it’s cheaper to get them reconditioned and sold again. Quicker turn around etc.

    TPS give you that as an option for MAF’s because frankly no one wants to pay £171 for a service item haha.


    Sent from my iPhone using Tapatalk
     
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  14. thegoal007

    thegoal007 Another S3 owner....

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    I remember when I first had battery issues I distinctly thought it was the battery and got it replaced (without checking anything!). turned out to be the alternator.

    expect to pay about half the price of a new bosch unit to get your own one reconditioned including fitting...well, that is what it was for me at the time.

    Not sure what a second hand one would go for plus the small agro of fitting it yourself, but you have choices.
    For me, with the confined space down there to DIY...erm, I think not.

    I had mine reconditioned 5 years back, so far so good..touch wood.
     
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  15. DCH

    DCH Registered User

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    I think I might try a new regulator first, then take my chances on a second hander

    Money is no object, but I’m Scottish

    DCH
     
  16. Maz

    Maz Moon is made of green cheese

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  17. desertstorm

    desertstorm Moderator Staff Member Moderator VCDS Map User

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    I bought a 90A alternator for my TT off Flea bay £20 delivered. It was a 90A item as my TT is a track car. I noticed in the pictures it had a Bosch exchange sticker on it and was only around 2 years old so in great condition. You may find something similar.
    https://www.ebay.co.uk/itm/VW-AUDI-SEAT-SKODA-ALTERNATOR-90A-BOSCH-0986041500/282594918255?
    As above you can take the regulator off without removing the alternator.
    You can get a new alternator from around £80 dependent on make https://www.autodoc.co.uk/car-parts/alternator-10450/audi/a3/a3-8l1/
     
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  18. DCH

    DCH Registered User

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    Regulator change seems to have fixed the issue, battery holding good charge and 14.5v running .....

    Big thanks to those who offered support on the thread and especially Maz for the regulator, appreciated

    Just like an Amsterdam Sauna, another happy ending

    DCH
     
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