Yes, I did read it but did not respond.
I do agree that periodic measurment of specific gravity, water level
maintaince, terminal post maintaince and general good battery care is conducive
to long life and minimal problems.
But I disagree about not doing equalizing charges while at anchor because for
the past eleven years I have lived entirely at anchor and do equalizing charges
from time to time without any problems (and without removing the cell caps).
Now the battery box cover is preforated peg-board, but in the future I will
make a solid cover with a vent fan rigged to come on whenever the battery is
being charged and blow the fumes overboard through a fitting with bronze wool
inside as a flame stopper.
And yes, almost all of us know that charging, especially an equalizing charge
which is a deliberate overcharge, produces large amounts of oxygen and
hydrogen, a very explosive mixture.
We also know that hydrogen/oxygen production is part of normal battery
operation. It is the buildup of the gasses in the battery area expanding to
find a source of ignition we must avoid. Once the gas is ignited the flame
wall will travel into the battery and there the confinement of expanding gasses
may (not always, I have experienced two battery explosions that merely blew the
caps off without breaching the case) break the battery case and make a big mess.
In the two cases of battery explosions I mentioned in my original message there
was no obvious source of ignition present. In both cases the people involved
eventually came to believe that the source of ignition was inside the battery.
The point of the whole message was to ask if anyone on the list had also
experienced a battery explosion and had some more evidence pointing to the
source of ignition being inside the battery.
Norm
S/V Bandersnatch
Lying Julington Creek FL
30 07.72N 081 38.4W
----- Original Message -----
From: LA Licata
To: Norm of Bandersnatch
Sent: 12/31/2007 4:48:03 AM
Subject: Fwd: [Liveaboard] Battery Explosions
Norm, did U get this?
lee
Begin forwarded message:
From: LA Licata <[EMAIL PROTECTED]>
Date: December 30, 2007 22:11:27 GMT+02:00
To: LIVE_ABOARD <[email protected]>, Norm of Bandersnatch <[EMAIL
PROTECTED]>
Subject: Re: [Liveaboard] Battery Explosions
Norm, from my experience on nuclear subs, battery explosions are usually called
by excessive buildup of Hydrogen gas that comes from excessive charging,
overcharging, or charging too fast. Then a spark, then the boom.
During equalization charges, the amount of hydrogen gas that is given off can
be a lot so a well ventilated battery area is necessary. Normal charges also
tend to have gas come off, but it should be a lot less, if all is going normal.
I also tend to remove all caps before equalizations to help the gas escape.
I never would do an equalization at sea, even at anchor. I would wait until I
was in port and shutdown.
Battery explosions can also occur if cells short somehow. That can be
especially "explosive" during an equalization charge.
Much can be learned if battery specific gravity is monitored routinely and
water levels are maintained.
Also, not too deeply discharging the battery can go a long way toward
minimizing the the potential of inter-cell shorting.
And, battery connections need to be clean and tight at all times to minimize
heat buildup, which could cause an explosive in a hydrogen rich or gas fume
rich environment.
Lee
On Dec 30, 2007, at 19:56 , Norm of Bandersnatch wrote:
Ann-Marie,
While I have no doubt you are correct in all you say, but I would like to
hear your explaination for batteries exploding during charge.
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