Mailing List Archive Mailing List Archive
All, please read this stuff below. JJ is correct, this other guy is dealing
out horrendous misinformation. The chemical reaction he cites is why a
battery works and charges and describes the reuptake and completion of both
reactions. I am embarrassed for the poor guy with what he concludes since he
says he is a chemical engineer. The fact is that when the reaction gets
unbalanced , or can not keep up, as in overcharge, discharge, heat, or
obstruction in the gas spaces of the gel, then the reaction yields hydrogen
and that pressurizes the container and blows out the vents.
If you want to see this in action, place a battery on charge in a tub of
water and see for yourself, or just spray one with Windex and see what I
mean. It is a crime that somebody can get on there with this level of
arrogant misinformation.
This fact of life, and anyone who has ever dealt with batteries in an sealed
container knows this, and anyone who has ever been diving with a light or
scooter knows this, or should know it.
Now , the other point Jarrod makes is that the lid must not be barrel sealed
or the o ring contained or trapped. The reason is twofold: one it is a bitch
to get off, and two, if it does blow, you want the o ring to extrude rather
than having the lid fragment all over you, or worse.
We have developed lights for the WKPP for years, and we know what we are
talking about, and the lights I have and use are perfect for diving.
-----Original Message-----
From: George_Irvine@Mo*
Sent: Wednesday, May 23, 2001 11:55 AM
To: trey@ne*.co*
Subject: Fwd: Re: EE and steel screws in aluminum (was Re: halcyon vs
DiveRite)
---------------------- Forwarded by George Irvine/CSC/CCM/CCI on 05/23/2001
11:53 AM ---------------------------
Jarrod Jablonski <JJ@Ha*.ne*> on 05/23/2001 10:54:45 AM
To: George_Irvine@Co*.co*
cc:
Subject: Fwd: Re: EE and steel screws in aluminum (was Re: halcyon vs
DiveRite)
Whats up with this?
>Delivered-To: halmail-jj@ha*.ne*
>User-Agent: Microsoft-Outlook-Express-Macintosh-Edition/5.02.2022
>Date: Wed, 23 May 2001 10:33:23 -0400
>Subject: Re: EE and steel screws in aluminum (was Re: halcyon vs DiveRite)
>From: Jim Cobb <cobber@ci*.co*>
>To: Olaf Trygve Berglihn <olafb@pv*.or*>, Jarrod Jablonski
<JJ@Ha*.ne*>
>CC: <techdiver@aquanaut.com>
>
>I suppose the issue is do you place your bets on nobody ever overcharging
>their battery or do you figure that sooner or later someone will and plan
>accordingly?
>
>This is pretty much a no-brainer if you ask me. I think there are too many
>rocket scientists in this sport to do it any good.
>
> Jim
> -------------------------------------------------------------------
> Learn About Trimix at http://www.cisatlantic.com/trimix/
>
> > From: Olaf Trygve Berglihn <olafb@pv*.or*>
> > Date: 23 May 2001 15:04:38 +0200
> > To: Jarrod Jablonski <JJ@Ha*.ne*>
> > Cc: techdiver@aquanaut.com
> > Subject: Re: EE and steel screws in aluminum (was Re: halcyon vs
DiveRite)
> >
> > Jarrod Jablonski <JJ@Ha*.ne*> writes:
> >
> >> Captured o-rings are dangerous due to combustion from battery off
> >> gassing and are not recommended.
> >
> > This is an issue when charging, but not really when discharging. Also,
> > the lead-gel YUASA batteries used (don't have it here in front of me,
> > but I think it is YUASA), are able to absorb the gas produced to a
> > certain degree.
> >
> > The basic chemical reaction is as follows:
> >
> > [anode] PbO_2 + 4H^+ + SO_4^{2-} = PbSO_4 + 2H2O
> > [cathode] Pb + SO_4^{2-} = PbSO_4 + 2e^-
> > [overall] PbO_2 + 2H_2SO_4 + Pb = 2PbSO_4 + 2H2O
> >
> > Direction of equilibrium reactions:
> > ---> Discharge
> > <--- Charge
> >
> > During the final stage of the charging cycle there are competing
> > chemical reactions taking place. Water is decomposed to produce
> > hydrogen and oxygen gases. The charging efficiency drops dramatically
> > at this stage. The presence of bubbles causes a stirring action of the
> > acid, thus sulphuric acid is then mixed within the electrolyte.
> >
> > During the final stage of charging or under overcharge condition, the
> > charging energy is consumed for electrolytic decomposition of
> > water. Oxygen is released as gas from the positive plate into the
> > sealed cell compartment. The oxygen then rapidly diffuses through the
> > separator or cracks in the gel. The oxygen reacts with the moist
> > negative active material to form lead oxide. The oxidation of the
> > negative causes a slight depolarization and inhibits the release of
> > Hydrogen gas. The lead oxide reacts to form lead sulphate that on
> > further charge changes to form lead and sulphuric acid. This results
> > in no loss of oxygen or hydrogen and therefore eliminates the need to
> > add H_2O.
> >
> > Now, for the discharge part, there is no production of gaseous
> > hydrogen, and any (unlikely) hydrogen leaking out was most probably
> > produced by overcharge.
> >
> > Bottom line is: Do not overcharge - a decent charger will prevent
> > it. Let the battery sit for a while after charging before you close
> > the lid. Vent a canister that has not been used for a while.
> >
> > Gas in the canister that has leaked from the sealed battery during
> > dive is highly improbable, and I see no special reason to have a
> > o-ring system that can act as a relief for an explosion in the
> > canister that will not happen. I do not think this represent a danger
> > for a battery that has been well vented during charging and set to
> > rest before use.
> >
> > Please correct me if I missed something out here (is has been a while
> > since I graduated chem. eng.). Do you have any examples of hydrogen
> > gas trapped in the sealed battery that has caused explosion in a
> > canister - i.e. if the battery was vented during charging.
> >
> > Saying this, I have not yet had a leak in my apollo 14, and I'm
> > looking forward to going diving the next four days with my repaired
> > Goodman handle.
> >
> > Olaf
> > --
> > Olaf Trygve Berglihn <olafb@pv*.or*>
> > --
> > Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'.
> > Send subscribe/unsubscribe requests to
`techdiver-request@aquanaut.com'.
> >
Jarrod Jablonski
President- Global Underwater Explorers
CEO- Halcyon Manufacturing/Extreme Exposure
Halcyon Manufacturing www.halcyon.net
Extreme Exposure www.extreme-exposure.com
Halcyon manufacturing produces some of the scuba industry's most novel and
robust diving equipment designed by many of diving's most active explorers.
From the world record Halcyon rebreather to revolutionary lighting and
life support equipment our companies are revolutionizing the manufacturing
of aquatic equipment. Please visit some of our many web sites to gain a
better appreciation of these diverse activities.
Global Underwater Explorers www.gue.com
Global Underwater Explorers is a non-profit educational, research, and
exploratory organization. GUE regularly engages in international
expeditions has hundreds of dedicated members around the world. From entry
level technical diver training to advanced exploratory, research and
filming projects GUE is widely considered one of the world's most diverse
and capable aquatic organizations.
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