[A4] Dead Battery

[Sean Coriaty]

My first thought: bad ground.  Most cars have at least 2 major
grounds- one is obvious- just follow the negative lead of the battery
(the fat wire); also there is usually another ground wire/ strap
(often a flat metal shiny braided ribbon-like strap) connecting the
motor to the unibody or subframe (not sure about our A4s).  When the
scenario you described occurs to me, I usually disconnect the
ground(s), clean the contacts, then reconnect.  It makes for good
preventive maintenance to just do it every couple years or more
frequently in tough conditions (salty New England winters, for
example).
Second thought: bad battery cell.  This can be tested with a
multi-meter.  You took a reading with the car off- it should read
around 13-14 volts (your reading seems high, one indicator of a bad
cell).  But the second test is more important: with the meter on the
battery, have someone else try to start the car.  If voltage plummets
below, say, 10 or 11 volts, the battery is bad (usually bad cell).  By
doing this (meter while starting), you're testing the battery under
load.  Batteries with bad cells will usually hold a charge, but will
fail under load.
Glad you got her back on the road again so quickly.
Sean


> Wow, my battery died like I've never seen it before.
>
> Everything has been fine and dandy, no slow starting, no weird power
> problems, nothing wrong at all.  So I stopped on the way to work this
> morning to get a soda and when I come out to the car and turn the key
> everything goes black.  No dash lights.  No dome light.  No nothing.  Almost
> like the battery had been removed from the car when I went into the store.
> :)  The weird thing is that the after a minute stuff started to come back to
> life.  The dome light sorta works again, the dash lights try to come back,
> but there's not enough juice to turn the starter.  I suspect the battery and
> get a jump and head off to AutoZone, and stall the car half way there.  I've
> been driving a stick for 20 years and can count on one hand the number of
> times I've stalled a car, but apparently nerves make this type of thing more
> common.  Grrrr....
>
> Anyway, does anyone know why a battery would go completely gone and then
> slowly crawl back to life?  My volt meter is reading good (15-17volts) and
> the car ran great after I got it started.  This hit me completely by
> surprise and there was no warning of a bad battery at all.
>
> 1998 A4 Q Sport
> --
> Later...                                                                  ?
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> Richard                                                               ?
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