What would pop the caps off the battery?

Discussion in 'General Motoring' started by Patrick Keenan, Oct 20, 2006.

  1. My '92 240 wagon has been running well and I've been driving it all day.
    However, when I just went to move it into my parking spot from the street,
    there was a bang.

    Opening the hood, the caps were blown off the battery and while there is
    some power - the locks and the dome light work - there is no response from
    the starter to the ignition key. As well, only a few of the warning lamps
    come on when the key is turned, instead of all of them. The fuses are
    intact.

    Guess I'm calling the garage first thing and then a towtruck, but would
    anyone have an idea of what's happened?

    thanks..
    Patrick Keenan
     
    Patrick Keenan, Oct 20, 2006
    #1
  2. Patrick Keenan

    Gary Heston Guest

    Overcharging. If the voltage regulator fails and the charging system puts
    too much power into the battery, it can boil the electrolyte and pop the
    caps off. You need to fix the charging system and replace the battery.


    Gary
     
    Gary Heston, Oct 20, 2006
    #2
  3. Patrick Keenan

    Mike F Guest

    Actually the electrolyte isn't boiling - you're breaking down the water
    into Hydrogen and Water. One spark (sometimes can even come from inside
    the failing battery) and you have anywhere from a minor mess to serious
    damage, depending on how lucky you are. But I agree - check the
    charging voltage and definitely get a new battery. If the battery fails
    in a certain way, one cell can be shorted, the other 5 will be
    overcharging even at the correct "normal" system voltage, so the
    charging voltage may be OK.

    --
    Mike F.
    Thornhill (near Toronto), Ont.

    Replace tt with t (twice!) and remove parentheses to email me directly.
    (But I check the newsgroup more often than this email address.)
     
    Mike F, Oct 20, 2006
    #3
  4. Thanks to all for the hints. Towtruck's on its way, and I'm glad to know
    that this electrical problem likely isn't terminal (so to speak).

    Patrick Keenan
     
    Patrick Keenan, Oct 20, 2006
    #4
  5. And it seems that the voltage regulator had failed and so over 16 volts was
    present. New battery, rebuilt alternator, problem is solved.

    Thanks again
    Patrick Keenan
     
    Patrick Keenan, Oct 20, 2006
    #5
  6. Maybe it's a Volvo thing ;-)

    My old 145 did that twice, but each time the battery actually blew up. The
    first time it was on a cold morning, the second time it was 122 degrees in
    the shade and the car was parked in the sun. Both times I hit the starter
    and heard a POP. The mist coming from under the hood told me what had
    happened. The hydrogen that is produced in normal charging had built up and
    something in the starting process set it off. A nice chemistry
    demonstration, but not helpful in getting anywhere.

    Mike
     
    Michael Pardee, Oct 23, 2006
    #6
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