Astra Battery/Alternator Warning Light - What Could Cause It To Come On?

Discussion in 'Astra' started by Dan Ricketts, Dec 12, 2003.

  1. Dan Ricketts

    Dan Ricketts Guest

    Hi All,

    Recently started having problems with the battery/alternator warning light
    on my '93 Astra 1.4i. A few weeks ago (during that horrendous weather) the
    fanbelt started squealing, resulting in the warning light illuminating to
    varying degrees.

    I replaced the belt on Wednesday and as far as I can tell it is a more or
    less the correct tension (~0.5 inch play), but the light still insists on
    illuminating. Usually it is relatively dim (i.e. only really visible with
    the dash lights turned down), but I've also found that when indicating
    (bearing in mind I'm also running dipped headlights, fan on 1, rear
    demister, wipers, headunit and sub/amp) the rev counter rises and falls
    slightly and the warning light & headlights brighten & dim in time to the
    flashing. I realise I'm putting a fair old strain on my cars electrical
    system, but before it's had no problems coping.

    The alternator was replaced just over a year ago, the battery (Varta, sealed
    maintenance free) is approx 2.5 years old. However the battery has been
    pretty much completely discharged 2 or 3 times (due to the failure of the
    previous alternator).

    I've got a nasty feeling that it's the battery causing this, but I always
    thought that it simply 'regulated' the fluctuating voltage output from the
    alternator, as opposed to powering the vehicle whilst running. What sort of
    checks can I do on the electrical system in order to track down the location
    of the fault?

    Many thanks in advance!

    Dan Ricketts, Dec 12, 2003
  2. Dan Ricketts

    Big Dave Guest

    Even though the battery is sealed, have you checked the electrolyte levels?

    I had one a few years ago that needed topping up.

    Big Dave, Dec 12, 2003
  3. Dan Ricketts

    mike Guest

    By far the easiest would be to fit another battery, even just a mate's one.
    see if it goes away.
    i doubt that a shafted battery would cause the ignition light to dimly glow,
    so my thoughts lie with maybe the regulator pack/diodes in the alternator
    being a bit sick somewhere.
    but i also agree with your loading theory, it is alot to ask, so might just
    be normal.

    a basic check would be to measure the battery after standing for say a night
    before starting.
    should be well better than 12VDC, as high as 13VDC if it is in good nick.
    start the car & the volts should climb with a maximum being about 14.5VDC at
    high revs.
    there is a point, (1200-1500rpm) where the alternator & it's box of tricks
    should not let the volts go any higher across the battery.
    if the volts continues to rise (over 14.5VDC) when going past about 2000rpm
    then i'd go for a damaged battery.
    if the volts across the battery never reaches into the 14VDC region,even
    after a long run(when it should be fully charged)
    then i'd plumb for a dicky alternator pack or maybe a suphated or buckled
    plates fault with the battery.

    best bet though, as i said, stick a mates battery on first.
    that should give you a good pointer.
    bearing in mind the battery age, i'd point my finger there!

    mike, Dec 12, 2003
  4. Dan Ricketts

    Me2 Guest

    Check the earth wire at the gearbox for damage/corrosion.
    Me2, Dec 13, 2003
  5. Dan Ricketts

    Chris Nowak Guest

    Your fault description is just that of a failure of alternator rectifier
    pack (built into alternator). If you measure battery voltage during idle and
    its less than 13v that would just about seal it for me - another alternator

    Best of luck.
    Chris Nowak, Dec 14, 2003
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