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RE: Helping the batteries perfom in the cold.

        Hydrogen is both very dangerous and safe.  It is dangerouse because
of its flamability.  It is safe because it diffuses extremely quickly.
Before the very light hydrogen gas could pool at a ceiling it would be even
diffused throughout the room (garage). 
        t is important that you  open the battery covers (hood and seat)
while charging.  Closing the hood while charging would likely expose the
charger timer contacts to an explosive concentration of hydrogen.  With the
hood open you probably never see an explosive concentration except in the
battery or immmediately around the battery fill caps.  I personally charge
my E15 in a closed 2 car garage and haven't blown it up yet.

> -Steve Naugler
> -e mail address:  snaugler rodel com
> ----------
> From:         David Roden[SMTP:roden ald net]
> Sent:         Saturday, January 02, 1999 9:38 PM
> To:   Max Hall; elec-trak cosmos5 phy tufts edu
> Subject:      Re: Helping the batteries perfom in the cold.
> From:                 "Max Hall" <maxo iname com>
> To:                   "elec-trak discussion list"
> <elec-trak cosmos5 phy tufts edu>
> Subject:              Helping the batteries perfom in the cold.
> Date sent:            Sat, 2 Jan 1999 19:32:35 -0500
> > Next question to all you battery-powered people:
> (Energizer bunny?)
> > 
> > To help my E15 work well out there in the cold, does it not make sense
> to
> > keep the thing as warm as toast (ok, say, 65 degrees F) before I put it
> to
> > work?
> Yes.  Every battery has a thermal capacity curve.
> > 
> > I imagine that those big bad batteries have huge heat capacity, (I 
> > mean,
> > specific heat of lead is high) and that they will cool very slowly if
> they
> > come out of the garage at 65. (ANd operation is exothermic; they give
> off
> > some heat as they work, yes?)
> > 
> Yes and yes.  They hold heat mainly because they are massive.  Every 
> battery has internal resistance, so they generate heat as they work 
> (though I'm not sure it's very much, given the relatively relaxed rate 
> at 
> which the ET asks them to work).
> > One would, in an unheated garage, want to be very careful about
> ventilation
> > especailly during charging, of course.
> Someone may disagree with me, but I'm of the opinion that most domestic 
> garages are large enough (and leaky enough) that hydrogen buildup is not 
> really a concern, given the number of batteries and the rate of charge 
> an 
> ET uses.  I don't have any special garage ventilation provisions for 
> either my ET or my electric car -- although I used an induction motor 
> blower to exhaust the air from the car's battery boxes when I had 
> flooded 
> batteries in it; a car is much smaller than a garage.
> I can see that you'd be more concerned in a heated garage, especially if 
> the heating system used a standing pilot.  But unlike gasoline fumes, 
> which are heavier than air, hydrogen would collect (if it collected at 
> all) near the ceiling.  I think.
> I just can't see six golf car batteries evolving enough hydrogen to 
> worry 
> about, as long as it's not held captive in a small space.
> Anyone have any other thoughts?
> PS: I wish the person in charge of this mailing list would program it so 
> that the reply-to field in each message contained the posting address 
> for 
> the list.  If I forget and just click "reply," the reply goes only to 
> the 
> posting contributor, rather than to the entire list.  I bet we all miss 
> some good, interesting stuff that way.
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