Bad smells from over charging lead acid batteries

Discussion in 'Electronic Design' started by ethan.petersen@gmail.com, Mar 16, 2009.

  1. Guest

    Over the weekend someone had left a charger on a lead acid battery,
    seriously overcharging the battery. It stunk up the whole shop with a
    sulfur smell. I know when you overcharge you get hydrogen and oxygen
    gas, and from the smell there is obviously some sulfur. That exhausts
    my knowledge of battery chemistry, does anyone know what the actual
    chemistry is?

    Nearby we had some copper tubing that was discolored. Some of the
    shop guys blamed that on the gas from the battery. Is that plausable?

    Ethan
     
    , Mar 16, 2009
    #1
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  2. Glen Walpert Guest

    On Mon, 16 Mar 2009 11:10:20 -0700 (PDT), Tim Shoppa
    <> wrote:

    >On Mar 16, 1:15 pm, wrote:
    >> Over the weekend someone had left a charger on a lead acid battery,
    >> seriously overcharging the battery.  It stunk up the whole shop with a
    >> sulfur smell.  I know when you overcharge you get hydrogen and oxygen
    >> gas, and from the smell there is obviously some sulfur.  That exhausts
    >> my knowledge of battery chemistry, does anyone know what the actual
    >> chemistry is?

    >
    >Actually the "sulfur smell" is hydrogen sulfide. Sulfur by itself
    >doesn't smell that bad. There was no shortage of hydrogen produced in
    >overcharging the battery, but hydrogen by itself doesn't really have a
    >smell. The free hydrogen combines with other random atoms it finds,
    >and even though sulfur isn't the most common element, when hydrogen
    >combines with sulfur in a confied space the result stinks to high
    >heaven.
    >
    >> Nearby we had some copper tubing that was discolored.  Some of the
    >> shop guys blamed that on the gas from the battery.  Is that plausable?

    >
    >The green tinted copper corrosion is copper sulfate. I think the
    >relation to your previous question, is that this shows that there is
    >no real shortage of sulfur compounds in your room. Blaming the
    >hydrogen for the presence of sulfur compounds is a little like blaming
    >the sun for letting you see ugly women :).


    Seriously overcharged lead acid batteries emit more than just
    hydrogen. The bursting bubbles cause electrolyte misting and
    evaporation, with enough flow rate to carry significant acid out of
    the battery, and in severe cases the electrolyte can boil. There are
    also a number of other reactions going on including one which releases
    small amounts of Stibene from the Antimony (Sb) used to strengthen the
    lead alloy plates.

    (Normal charging releases pretty much the same stuff in smaller
    quantities; hence TFM recommends ventilation.)

    www.apcmedia.com/salestools/SADE-5TNQZQ_R1_EN.pdf
    http://www.springerlink.com/content/m1660445062t2054/

    ---------
    Stibine
    From Wikipedia, the free encyclopedia

    Stibine is the chemical compound with the formula SbH3. This
    colourless gas is the principal covalent hydride of antimony and a
    heavy analogue of ammonia. The molecule is pyramidal with H–Sb–H
    angles of 91.7° and Sb–H distances of 1.707 Å (170.7 pm). This gas has
    an offensive smell like hydrogen sulfide (rotten eggs).

    Safety

    SbH3 is an unstable flammable gas. It is highly toxic, with an LC50 of
    100 ppm in mice. Fortunately, SbH3 is so unstable that it is rarely
    encountered outside of laboratories.

    Toxicology

    The toxicity of stibine is distinct from that of other antimony
    compounds, but similar to that of arsine.[6] Stibine binds to the
    haemoglobin of red blood cells, causing them to be destroyed by the
    body. Most cases of stibine poisoning have been accompanied by arsine
    poisoning, although animal studies indicate that their toxicities are
    equivalent. The first signs of exposure, which can take several hours
    to become apparent, are headaches, vertigo and nausea, followed by the
    symptoms of hemolytic anemia (high levels of unconjugated bilirubin),
    hemoglobinuria and nephropathy.
     
    Glen Walpert, Mar 16, 2009
    #2
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  3. richard Guest

    RST Engineering (jw) wrote:
    > The "acid" in a lead-acid battery is sulfuric acid (H2SO4). When you
    > overcharge a battery it generally gets hot enought to boil the acid, which
    > in turn vaporizes a fraction of the acid. THe acid vapor escapes through
    > the vented caps of the battery and is quite happy to recondense to liquid
    > acid on anything cool in the area ... like copper tubing at room
    > temperature. THe discoloration is a sulfur compound of copper, either the
    > sulfate or the sulfide. One is green and one is black but I disrember which
    > is which.
    >


    The sulphate is blue and the sulphide is black.
    But does H2SO4 react with copper ?
     
    richard, Mar 19, 2009
    #3
  4. Jasen Betts Guest

    On 2009-03-19, richard <> wrote:
    > RST Engineering (jw) wrote:
    >> The "acid" in a lead-acid battery is sulfuric acid (H2SO4). When you
    >> overcharge a battery it generally gets hot enought to boil the acid, which
    >> in turn vaporizes a fraction of the acid. THe acid vapor escapes through
    >> the vented caps of the battery and is quite happy to recondense to liquid
    >> acid on anything cool in the area ... like copper tubing at room
    >> temperature. THe discoloration is a sulfur compound of copper, either the
    >> sulfate or the sulfide. One is green and one is black but I disrember which
    >> is which.
    >>

    >
    > The sulphate is blue and the sulphide is black.
    > But does H2SO4 react with copper ?


    CuSO4 is stable, so yes, I don't think it's a vigourous reaction at
    room temperature though,
     
    Jasen Betts, Mar 20, 2009
    #4
  5. richard Guest

    JosephKK wrote:
    > On Thu, 19 Mar 2009 23:18:51 +0000, richard
    > <> wrote:
    >
    >
    >>RST Engineering (jw) wrote:
    >>
    >>>The "acid" in a lead-acid battery is sulfuric acid (H2SO4). When you
    >>>overcharge a battery it generally gets hot enought to boil the acid, which
    >>>in turn vaporizes a fraction of the acid. THe acid vapor escapes through
    >>>the vented caps of the battery and is quite happy to recondense to liquid
    >>>acid on anything cool in the area ... like copper tubing at room
    >>>temperature. THe discoloration is a sulfur compound of copper, either the
    >>>sulfate or the sulfide. One is green and one is black but I disrember which
    >>>is which.
    >>>

    >>
    >>The sulphate is blue and the sulphide is black.
    >>But does H2SO4 react with copper ?

    >
    >
    > Yes. Quite vigorously given the chance (like drop a bit in 1 molar
    > H2SO4), with much release of H2 gas. Vapors will corrode copper pipe
    > in a hurry.
    > .


    Sorry, I don't believe that. Copper is below Hydrogen in the electrochemical series (along with similar "inert" metals - Gold,
    Silver, Hg)

    Cu does not react with H2SO4 appreciably at room temperature.

    In order to increase the reaction rate between Zn & H2SO4, one adds a crystal or drop of CuSO4 solution. The Zn reacts with the
    CuSO4 precipitating Cu which creates a "Zinc-Copper couple" which (I guess) makes it easier for the Zn to go into solution (like
    rusting).

    Do the experiment (and remember to add the concentrated acid to the water - and not the other way round).
     
    richard, Mar 26, 2009
    #5
  6. richard Guest

    JosephKK wrote:
    > On Thu, 26 Mar 2009 21:33:07 +0000, richard
    > <> wrote:
    >
    >
    >>JosephKK wrote:
    >>
    >>>On Thu, 19 Mar 2009 23:18:51 +0000, richard
    >>><> wrote:
    >>>
    >>>
    >>>
    >>>>RST Engineering (jw) wrote:
    >>>>
    >>>>
    >>>>>The "acid" in a lead-acid battery is sulfuric acid (H2SO4). When you
    >>>>>overcharge a battery it generally gets hot enought to boil the acid, which
    >>>>>in turn vaporizes a fraction of the acid. THe acid vapor escapes through
    >>>>>the vented caps of the battery and is quite happy to recondense to liquid
    >>>>>acid on anything cool in the area ... like copper tubing at room
    >>>>>temperature. THe discoloration is a sulfur compound of copper, either the
    >>>>>sulfate or the sulfide. One is green and one is black but I disrember which
    >>>>>is which.
    >>>>>
    >>>>
    >>>>The sulphate is blue and the sulphide is black.
    >>>>But does H2SO4 react with copper ?
    >>>
    >>>
    >>>Yes. Quite vigorously given the chance (like drop a bit in 1 molar
    >>>H2SO4), with much release of H2 gas. Vapors will corrode copper pipe
    >>>in a hurry.
    >>> .

    >>
    >>Sorry, I don't believe that. Copper is below Hydrogen in the electrochemical series (along with similar "inert" metals - Gold,
    >>Silver, Hg)

    >
    >
    > The issue is not the H2, the issue is the (hot) H2SO4 {(aq)?} vapor.
    > See:
    >
    > http://jchemed.chem.wisc.edu/JCEsoft/CCA/CCA3/MAIN/CUNASID/PAGE1.HTM


    Thanks for the reference.
    I had not tried with hot conc H2SO4 - only cold dilute (eg 1 molar) - to confirm my memory before going public.

    >
    > And OK not vigorously without a little bit of zinc to catalyze and
    > participate. See also brass fittings.
    >
    > Was the stuff on the copper pipe blue or green? Likely to be copper
    > sulfate or similar. IIRC No mention yet of anything else in the
    > vicinity that could produce copper salts.
    > Perhaps with an H2O2 intermediary producing copper oxide (which is
    > conveniently green). The 4th oxygen from the sulfate ion may produce
    > H2O2.
    >
    > 2 H2SO4(aq) + 2 Cu(s) yeilds SO2(g) + H2(g) + CuSO4 + CuO + H2O ??
    >
    > This does not produce any H2O2 and the CuO should preciptiate.
    >
    >>Cu does not react with H2SO4 appreciably at room temperature.
    >>
    >>In order to increase the reaction rate between Zn & H2SO4, one adds a crystal or drop of CuSO4 solution. The Zn reacts with the
    >>CuSO4 precipitating Cu which creates a "Zinc-Copper couple" which (I guess) makes it easier for the Zn to go into solution (like
    >>rusting).
    >>
    >>Do the experiment (and remember to add the concentrated acid to the water - and not the other way round).

    >


    remnants of flux (perhaps containing Ammonium Chloride) can cause green corrosion
    >
    > Alas, i do not currently have shelf access to such simple chemicals
    > these days.


    Yes, more difficult to obtain as pure chemicals these days, but some drain cleaners contain "commercial" H2SO4

    If I had to make H2SO4 I'd do it with sulphur, to make SO2 and pass that with air over Vanadium Pentoxide to make SO3


    I think that Glen Walpert gave the most plausible answer - certainly the most interesting.
     
    richard, Mar 28, 2009
    #6
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