98 V70 Battery Discharging

Discussion in 'Volvo V70' started by Inno, Jan 12, 2010.

  1. Inno

    Inno Guest

    My V70 seems to have an electrical leak: when I put an ohm-meter on
    the battery cables (with battery removed and car turned off) it shows
    full conductivity. This can't be good for battery life! I have
    pulled out every fuse in the two fuse blocks under the hood one at a
    time, and none of them cut off the circuit.

    I have an in-line fuse for my trailer lights and pulling that did
    nothing.

    Any idea where my juice is going? What circuits do not go through the
    fuses?

    Also, on related note: how long does it take to charge a 12 Volt
    battery to full power on a 10A battery charger? I don't want to leave
    it on too long or not long enough.
     
    Inno, Jan 12, 2010
    #1
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  2. Inno

    Roger Mills Guest

    In an earlier contribution to this discussion,

    What do you mean by "full conductivity"? Zero ohms? If so, with the battery
    connected, a very high (theoretically infinite) current would flow - which
    is very unlikely!

    What are the original symptoms which you are trying to investigate? Is the
    battery going flat with everything (apparently) turned off? If so, how long
    is it taking to go flat?

    When re-charging a battery off the car, most chargers will drop to a trickle
    when the battery is nearly fully charged, so over-charging shouldn't be a
    problem. If the battery is completely flat, it will take quite a few hours -
    probably over-night - to charge fully.
    --
    Cheers,
    Roger
    ______
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    Roger Mills, Jan 12, 2010
    #2
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  3. Inno

    James Sweet Guest



    You're not doing it right, you can't just measure the impedance across
    the leads, any capacitors in electronic devices will appear as a short
    circuit until they charge. You need to disconnect one battery lead, then
    set the meter to measure DC Amps and put one probe on the empty battery
    terminal and the other on the lead that normally occupies it.
     
    James Sweet, Jan 13, 2010
    #3
  4. Inno

    Roger Mills Guest

    In an earlier contribution to this discussion,
    But don't try to start the engine with the ammeter in series with the
    battery lead - unless it's a very hefty one which can handle several hundred
    amps - in which case it won't be much use for measuring a small leakage
    current.

    I'm not sure how much/little current you're looking for - it depends on how
    quickly the battery is discharging. For example, (assuming battery capacity
    is linear - which it isn't, so this is only approximate) if (say) 100mA is
    flowing (equivalent to a 1.2 watt lamp being on) a 100 amp-hour battery
    would take 1000 hours (over 40 days) to discharge - so you wouldn't notice
    it because it would get charged up by running the engine in the meantime. So
    you must be looking for a lot more than this - maybe one amp or more
    (discharging in about 4 days). If it still happens with all the fuses out,
    it suggests that it must be something like leaking diodes or smoothing
    capacitor in the alternator. To check this, you'd have to disconnect the red
    cable from the alternator - but don't let the bare end of the cable touch
    anything earthy - so disconnect it with the battery disconnected, and
    insulate it before re-connecting the battery!
    --
    Cheers,
    Roger
    ______
    Email address maintained for newsgroup use only, and not regularly
    monitored.. Messages sent to it may not be read for several weeks.
    PLEASE REPLY TO NEWSGROUP!
     
    Roger Mills, Jan 13, 2010
    #4
  5. Inno

    Dave Guest

    My V70 (UK) has also fuses in the trunk and at the end of the dash.

    Dave
     
    Dave, Jan 13, 2010
    #5
  6. Inno

    Inno Guest

    Can you be more specific as to where in the trunk and end of dash? Is
    yours a 1998?
     
    Inno, Jan 13, 2010
    #6
  7. Inno

    Inno Guest

    Yes, my battery was going flat after sitting for 2 or 3 days. I tried
    a (newer) battery and same problem. While driving, my ScanGauge shows
    between 13.5 and13.7 V, so it seems the alternator is charging ok,
    unless those readings are low. Lights and accessories seem to work
    fine while driving.

    I did not try to get an exact measurement on the meter: the needle
    went right to the peg stop. I suppose I should zero it first and get
    something more specific.

    Thanks for your interest.
     
    Inno, Jan 13, 2010
    #7
  8. Inno

    Inno Guest

    OK, I can try that. What should the reading be with this process, 0
    DC amps?
     
    Inno, Jan 13, 2010
    #8
  9. Inno

    Inno Guest

    Thanks!

    I did consider that the amp might be the source of the leak but did
    not know how to test. If I can find the end of the red cable I will
    do as you suggest. Is it accessible from the engine compartment or
    must I crawl in the dirty snow under the car? (Located in Toronto.)
     
    Inno, Jan 13, 2010
    #9
  10. Inno

    James Sweet Guest


    Yes.

    You should see no more than a few tens of milliamps.
     
    James Sweet, Jan 14, 2010
    #10
  11. Inno

    Dave Guest

    Mine is a 2004. Looking from the rear of the car,there is a panel in
    the lefthand side just inside the tailgate. The dash box is under a
    cover at the right hand end of the dash.

    Dave
     
    Dave, Jan 14, 2010
    #11
  12. Inno

    Roger Mills Guest

    In an earlier contribution to this discussion,
    'Fraid you can't deduce much from that - other than if it 'happens' to be in
    the same place. A 2004 V70 (built on the S80 platform) is a completely
    different animal from the 1998 model (derived from the 850).
    --
    Cheers,
    Roger
    ______
    Email address maintained for newsgroup use only, and not regularly
    monitored.. Messages sent to it may not be read for several weeks.
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    Roger Mills, Jan 14, 2010
    #12
  13. Inno

    Roger Mills Guest

    In an earlier contribution to this discussion,
    Not sure what you mean by 'amp' but I assume that you're referring to the
    alternator.

    This is located at the front of the engine (on the left when standing in
    front of the car looking into the engine compartment) under the power
    steering reservoir. You should be able to get at from under the bonnet/hood
    (depending on whether Canadians use British or American terminology!)
    although things like power steering reservoir and auxilliary drive belt
    might get in the way a bit. [I don't think it would be any easier from
    *under* the car]. As far as I can see from my Haynes manual, the red cable
    should simply unplug - if you can get your hand in - it doesn't appear to
    need any tools. [But I could be wrong!]
    --
    Cheers,
    Roger
    ______
    Email address maintained for newsgroup use only, and not regularly
    monitored.. Messages sent to it may not be read for several weeks.
    PLEASE REPLY TO NEWSGROUP!
     
    Roger Mills, Jan 14, 2010
    #13
  14. Inno

    Inno Guest

    Thanks Roger. I will try to find that cable and pull it to see if that
    makes a difference.

    We call it the "hood" not "bonnet" by the way!
     
    Inno, Jan 14, 2010
    #14
  15. Inno

    Roger Mills Guest

    In an earlier contribution to this discussion,
    Shame on you! <g>

    [I was hoping that your British heritage would carry more weight than the
    proximity of your American Neighbo(u)rs].
    --
    Cheers,
    Roger
    ______
    Email address maintained for newsgroup use only, and not regularly
    monitored.. Messages sent to it may not be read for several weeks.
    PLEASE REPLY TO NEWSGROUP!
     
    Roger Mills, Jan 14, 2010
    #15
  16. Inno

    Inno Guest

    We do spell it neighbour (and colour etc.) But we wear our boots on
    our feet and Wellingtons are for flying.
     
    Inno, Jan 14, 2010
    #16
  17. Inno

    Inno Guest

    OK, I zeroed my meter and redid the tests:

    Resistance seems to be around 10 ohms, if I am reading it correctly,
    with battery removed.

    I also did the test with the battery in and there seems to be 3 amps
    coming through.

    I also did both tests with the red/white wire removed from the
    alternator and no difference.

    Thoughts?


     
    Inno, Jan 17, 2010
    #17
  18. Inno

    James Sweet Guest

    Ignore the resistance, as I said before, that's a worthless measurement
    in this case.

    3 Amps seems high to me, what I would do now is pull fuses one at a time
    and see when the current drops substantially. You might check the glove
    box light too, that getting stuck on is a common cause of a dead battery.

     
    James Sweet, Jan 17, 2010
    #18
  19. Inno

    Roger Mills Guest

    In an earlier contribution to this discussion,
    If you mean the thin red and white wire - that's only the sensor for the
    instrument lamp - you need to disconnect the *thick* red wire!
    --
    Cheers,
    Roger
    ______
    Email address maintained for newsgroup use only, and not regularly
    monitored.. Messages sent to it may not be read for several weeks.
    PLEASE REPLY TO NEWSGROUP!
     
    Roger Mills, Jan 17, 2010
    #19
  20. Inno

    Roger Mills Guest

    In an earlier contribution to this discussion,
    Agreed. But I've never seen a 36watt lamp in a glovebox!
    --
    Cheers,
    Roger
    ______
    Email address maintained for newsgroup use only, and not regularly
    monitored.. Messages sent to it may not be read for several weeks.
    PLEASE REPLY TO NEWSGROUP!
     
    Roger Mills, Jan 17, 2010
    #20
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