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Brand new battery, battery light on with cold start, blip accel and it goes away.

Discussion in 'A4/S4 forum(B5 Chassis)' started by jonnycraig, Jan 28, 2013.

  1. jonnycraig
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    jonnycraig Member

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    [Jan 28, 2013]
    Hi guys I have tried to search for this symptom, essentially like the title says.

    Any ideas, alternator is def putting out the 13.8 volts.

    Cheers

    Jonny

    (1996 B5 1.9 TDI 90bhp 1Z Engine)
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  3. Bradderz_1988
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    Bradderz_1988 Dont replace it, Upgrade it !!

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    [Jan 28, 2013]
    Battery should charge around 14.3/14.4 with no consumer load whats the battery voltage not running after 10 mins ?? The battery you have may look brand new but may have been sat on a shelf and in need of a 24 hour trickle charge battery should read around 12.6/12.7 new if its under 12.2 try a trickle charge see what that does also hook a multimeter up to the battery see what voltage you have with it at idle then raise it to 2k see what happens !!
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  4. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Jan 29, 2013]
    Craigs S4 does this very same thing.

    Start it up and the battery light is on and the voltmeter reads 12v. If you dont touch the throttle and leave it idling it stays at 12v and the light stays on. Give the throttle a poke to blip the revs and it jumps up to 14v and the light goes out, and it then charges fine even when idling from then on.

    Its been like that for a year, hes been ignoring it as alternator is a pig to get at and is expensive.

    Interestingly, it started after we put the engine in another car, so i had a bit of a feeling that it was a wiring issue, but i cant see anything wrong.
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  5. PAULF
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    PAULF Active Member

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    [Jan 29, 2013]
    Mrs PaulFs Avant 2.5TDi does similar - although if you leave it idling for a while, it also comes up. The light isn't on, just a lower charge.

    That's with different batteries and different alternators too.

    It may just be an Audi 'thing' - although I suspect a higher than normal resistance earth or contactor somewhere.
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  6. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Jan 29, 2013]
    I wouldnt say its normal, None of mine do it, and craigs didnt used to until we swapped the engine.
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  7. NineNails
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    NineNails Proud sponsor of the snack food industry

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    [Jan 29, 2013]
    Dunno if this is of any use but my old 90 did this exact same thing and it was the voltage regulator on the alternator. On those alternators you could change the v r with the brushes for about 12 quid. I don't know if you can do that with these
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