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Why Won't a Frozen Battery Start a Vehicle.

Discussion in 'Electronic Basics' started by Denny B, Jan 30, 2004.

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  1. Denny B

    Denny B Guest

    A battery that is perfectly good why when it is -30C
    won't it start a vehicle.
    Please note we are referring to a perfectly good battery
    and a totally functioning car.
    What is happening to the battery that it cannot crank
    the starter fast enough.
    Chemically something is happening inside the battery.
    Is it the electrolyte that freezes and chemically do what
    it should do? Does something happen to the lead plates?
    Does the 12 volts drop to a lower voltage? Does the current
    output of the battery drop?

    The cold is doing something to the battery What Is That
    Well informed auto mechanics please step up to the plate!

    I do not need to start my vehicle my spare battery connected
    in parallel with the frozen battery does that.

    If your frozen battery won't start your vehicle and you remove
    it and take it indoors and let it heat up to house temperature,
    after reinstall it on the vehicle' it will then start the vehicle.

    What is happening to the battery internally at -30C?

    Denny B
  2. Actually, Chemically something is NOT happening.
    Your Lead Acid battery needs heat to allow the acid to react on the lead
    to produce enough electron mobility. Denying the necessary voltage and

    It's pretty simple.

    How do you stop a fire?
    Remove: Fuel, or Air, or HEAT.

    | __O Thomas C. Sefranek
    |_-\<,_ Amateur Radio Operator: WA1RHP
    (*)/ (*) Bicycle mobile on 145.41, 448.625 MHz
  3. DarkMatter

    DarkMatter Guest

  4. JeffM

    JeffM Guest

    What is happening to the battery
    Yup. High school chemistry.
    How do you alter the rate of a chemical reaction?
    Change 1) concentration 2) surface area or 3) temperature
  5. Doug

    Doug Guest

    The other factor is an engine at -30C is much harder to crank as the oil is
    much thicker. It is also harder to start because gasoline doesn't vaporize
    as well.
  6. DarkMatter

    DarkMatter Guest

    Fuel charges are denser at colder temps and final pressure at TDC is
    greater. It isn't about vaporization as the exploded fuel actually
    delivers more energy. Ask any dragster racer if a cold dry day or a
    hot desert sun is better for the race.
  7. Bob Masta

    Bob Masta Guest

    The exploded fuel may contain more energy, but at really low
    temperatures (as the OP was talking about) it is a lot harder
    to vaporize and hence to get it to explode to begin with.
    (I doubt many dragsters run at below-freezing temperatures. )
    Gasoline is specially formulated for the season of the year in
    temperate climates. The winter formulation is much more volatile,
    specifically to address this problem. The relevant parameter
    here is "Reed Vapor Pressure". But they usually only formulate
    for broad temperature ranges, so you may only get a generic
    "winter" blend that is a compromise.

    Bob Masta

    D A Q A R T A
    Data AcQuisition And Real-Time Analysis
  8. Bill Vajk

    Bill Vajk Guest


    I'm chiming in because I hate to see loose language like
    this lead to misunderstandings by neophytes.

    Let's just get rid of that idea right now. Fuel in an
    internal combustion engine does not "explode," it burns
    at a finite rate depending on a number of variables. It
    is a fast burn, but hardly an eplosion.
  9. DarkMatter

    DarkMatter Guest

    Fuel does not get "vaporized" in a car's induction system. It gets
    atomized at best. Such task is no harder to perform in cold dense

    The carburetor or injector has no added work load on the starter.
    The denser charge does. It increases the TDC pressure in the

    The only thing that fire lag causes is the need for more cranking to
    occur until the car starts, it doesn't change the power required to do
    the job. Just the length of time it takes to do it... sometimes.

    A good set of platinum tipped plugs on a high energy ignition system
    all but negates that claim.
  10. DarkMatter

    DarkMatter Guest

    That is exactly where they would most like to race, and there are
    tracks all over the country. Ever heard of the "winternationals"?

    They very much so like cold whether on race day.
    Dragster operators formulate their own.
    You're nuts.
    Yeah, if we were talking about vapor. We are not.

    Reid vapor pressure (the proper spelling) is about the final
    pressure a volatile liquid reaches in a contained space. It varies
    with temperature, and has not a thing to do with hard starting cars in
    the winter. AGain, fuel in car induction systems gets atomized NOT
    Sorry, but octane rating determines the energy output of the fuel,
    as well as its ignition parameters. I don't see big swings in octane
    numbers at the pumps in winter locales. In fact, I don't see ANY
    swings. Your argument falls apart.
  11. DarkMatter

    DarkMatter Guest

    Ever heard a dragster engine "chime in"?

    Sure it is burning at a defined rate. Since that rate exceeds the
    speed of sound, we humans define it as an explosion. The forces
    created are combustion forces or can be argued as explosive forces.
    The language you should have chimed in on is the fact that cars do
    NOT "vaporize" their fuel charges.
  12. Zipperhead

    Zipperhead Guest

    You can always tell when a mechanic just had sex.

    He has one clean finger.
  13. DarkMatter

    DarkMatter Guest

    E W W W W WWwwwwwww!!!
  14. Bob Masta

    Bob Masta Guest

    It's a popular misconception that high octane means high energy.
    It doesn't, basically only determines anti-knock properties. The only
    reason high performance engines need higher octane is because they
    use higher compression ratios, either straight mechanical or due
    to supercharging. And difference in energy content is trivial.

    As for the seasonal RVP changes, my info does go back a "few"
    years. In the mid-70s I was an engineer at GM Cadillac, and we
    most definitely *did* have seasonal and regional RVP changes.
    When we were doing cold-start tests in the summer (in a huge
    drive-in chassis dynamometer cold-room), we had to take care to
    get the proper fuel blend. RVP was indeed the relevant parameter,
    whether you believe it or not. I expect that it affects cold-starts
    just as much now as it did then, and that gas companies still
    change it with the seasons. No, it won't show up on octane
    numbers... not that I think the station owners would run out and
    change the pump stickers every season anyway.

    Why not just keep the winter blend all year? Because in hot
    weather it causes vapor lock and similar problems.

    Incidentally, one other thing that helps a cold start is to
    have seriously retarded timing, so the ignition is pretty
    close to TDC. That was hard to do on the ignition systems
    of the early '70s, so I came up with a sneaky way to do
    it using only simple electronics, which I called ESS (Electronic
    Spark Selection). Cadillac only used it for a couple of model
    years before EST (Electronic Spark Timing) became standard,
    but ESS cost only $20 to add to a car, where EST cost $180.
    ESS also gave big fuel economy improvements compared to the
    stock system, since the timing for normal operation could
    be advanced farther. It didn't just operate at start, but allowed
    cheapo switches to change the timing. So I used manifold
    pressure switches and transmission speed switches that were
    already there to tailor the timing for best emissions and
    economy. Cheap and effective.

    Ahh, the good old days!

    Bob Masta

    D A Q A R T A
    Data AcQuisition And Real-Time Analysis
  15. You sure are, DimBulb!

    As has been noted the chemical reaction in the battery is far
    lower in colder temperatures, so the current available is lower.
    Chemical reactions are exponential functions WRT temperature
    (batteries die during the summer, but aren't stressed until
    winter). The "Cold Cranking Amps" spec attempts to quantify the
    current available at low temperature.

    The second major factor is the oil. The engine oil (and
    transmission fluid) is about the consistency of peanut butter,
    the engine needs far more torque from the starter, thus current
    from the battery, to turn over. Thus CCA is important.

    These two factors far outweigh any other engine or fuel dynamics.
  16. DarkMatter

    DarkMatter Guest

    Racers use 100 octane fuel so that they can run higher compression
    and get higher energy output. It yields higher energy in that it can
    be used in an internal combustion engine better. The number itself
    refers to its ability to only detonate when told, and not as a result
    of temperature or pressure.

    The fact that alcohol is now used to increase that number means that
    even less energy is produced by ethanol added fuels. True gasoline of
    higher octane numbers, however, does also produce higher levels of
    energy as measured in BTUs.

    Yer not gonna be able to **** with me on this one, because I am not
    one of your subjects that has the "popular misconception" which you
    describe. Try again.
  17. DarkMatter

    DarkMatter Guest

    The energy delivered is a direct function of final compressed
    cylinder pressure, and is far from trivial, dufus.
  18. DarkMatter

    DarkMatter Guest

    RVP was a big problem in HOT environs. Vapor lock was a problem in
    hot engines with the wrong fuel. Carbureted induction systems was the
    reason. Modern fuel injected engines won't see these issues, and fuel
    is a lot different these days as well.
  19. DarkMatter

    DarkMatter Guest

    No shit, but the consideration was for hot environs, not cold.
  20. DarkMatter

    DarkMatter Guest

    Since engines already typically operate from 10 to 30 degrees BEFORE
    TDC, ADVANCING it toward TDC would NOT be termed "seriously retarded".

    Your logic, perhaps, but not the engine timing.
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