Larry,

Satisfy my curiosity here. I've seen the aftermath of two battery
explosions so I know they happen and are serious when they do.
However, with all those cars racing around bouncing and jolting their
cheap, thin plate batteries that usually aren't replaced until the
motor won't turn over, I've never heard of an auto battery explosion.
I'm sure they happen but it's got to be statistically rare for one not
to have come to my direct notice.

I understand that the AGM cells in my boat are a wrapped sandwich of
glass mat and the lead plates. How can contact between these plates
be very likely? Is the boat just sitting there motionless more
likely to have these well supported plates bend than all those cars
sitting in unheated garages and out on the street? First, the
batteries have to discharge which seems pretty unlikely with the
cables disconnected. My wife has to have AAA jump start her car a
half dozen times a winter because she doesn't close the doors all the
way or leaves the lights on. No problem so far.

This seems like a several orders of magnitude lower risk than the boat
falling off the jackstands.

--

Roger Long

On Sun, 29 Oct 2006 13:27:48 GMT, "Roger Long"
wrote:

Satisfy my curiosity here. I've seen the aftermath of two battery
explosions so I know they happen and are serious when they do.

It's my understanding, perhaps incorrect, that most battery explosions
occur while charging. Charging releases hydrogen which can and will
explode under the right conditions - poor ventilation, spark, etc.

The risk of an idle battery exploding is just about nil, otherwise it
would be happening all the time.

Roger Long wrote:
Larry,

Satisfy my curiosity here. I've seen the aftermath of two battery
explosions so I know they happen and are serious when they do.
However, with all those cars racing around bouncing and jolting their
cheap, thin plate batteries that usually aren't replaced until the
motor won't turn over, I've never heard of an auto battery explosion.
I'm sure they happen but it's got to be statistically rare for one not
to have come to my direct notice.

I understand that the AGM cells in my boat are a wrapped sandwich of
glass mat and the lead plates. How can contact between these plates
be very likely? Is the boat just sitting there motionless more
likely to have these well supported plates bend than all those cars
sitting in unheated garages and out on the street? First, the
batteries have to discharge which seems pretty unlikely with the
cables disconnected. My wife has to have AAA jump start her car a
half dozen times a winter because she doesn't close the doors all the
way or leaves the lights on. No problem so far.

This seems like a several orders of magnitude lower risk than the boat
falling off the jackstands.


Roger,

Larry may have a different view, but my
understanding is that battery explosions
are almost always caused by the release
of explosive gas (usually caused by
overcharging). Battery installations in
boats typically involve small, closed
compartments. Contrast that with
automotive installations in which there
is usually a good flow of air through
the battery compartment and it becomes
clear why automotive battery explosions
are far less common than those in boats.

So perhaps the focus might be better
placed on adequate battery compartment
ventilation: a low-cost, low-tech
solution that could reduce the
probability of a battery explosion in a
boat to that of a similar battery in an
automobile.

I've seen no statistics on steam
explosions so I can't comment on that
except to agree that these would be as
likely in an automobile as they are in a
boat, and are virtually unheard of in
the former.

I do enthusiastically endorse Larry's
suggestion of a simple timer on an
unattended battery charger, BTW.

Chuck

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"Roger Long" wrote in news%11h.492$xw1.375
@twister.nyroc.rr.com:

I understand that the AGM cells in my boat are a wrapped sandwich of
glass mat and the lead plates. How can contact between these plates
be very likely? Is the boat just sitting there motionless more
likely to have these well supported plates bend than all those cars
sitting in unheated garages and out on the street? First, the
batteries have to discharge which seems pretty unlikely with the
cables disconnected. My wife has to have AAA jump start her car a
half dozen times a winter because she doesn't close the doors all the
way or leaves the lights on. No problem so far.


Oh, the cars have their share of battery explosions, usually from the
unfused alternator diodes shorting to ground or the frozen starter with
the shorted commutator. However, it's not much of a mess in a car where
the acid bath is so easily washed away as soon as it happens, and is,
mostly, forgotten, unless it exploded when the WIFE turned the key,
which, of course, is all YOUR fault. The batteries, usually, don't short
internally plate-to-plate because of the separator....as long as they
don't get hot when the supercharger screws up and puts 40A to them for a
couple of weeks while you're ashore or the boat alternator diodes that
ALWAYS have DC voltage on them with the key off, short same as the car.

I had a red AGM battery that came with my government-surplus Chevy diesel
stepvan "go off", by the way. That was an internal short. It didn't
explode, I suppose because the short wasn't a dead short. It simply
MELTED as the plates became so hot it blew the safety pressure valves out
of it and boiled the electrolyte in the gauze into steaming sulfuric
acid. The cell that shorted, took out all the other cells because it
melted from its cylinder into their cylinders. I swapped it with an AGM
dealer who gave me a nice credit against another AGM battery priced like
a Lexus front end. Luckily, the one that melted opened from post to post
so it didn't also short the other one in parallel with it used to crank
the 6.2L diesel V-8...which now runs on free frying oil from 3 chinese
restaurants...(c; (www.frybrid.com)

Larry
--
I sure hope Halloween comes real soon....
I've run out of Halloween candy THREE TIMES SO FAR!

Larry wrote:
"Roger Long" wrote in news%11h.492$xw1.375
@twister.nyroc.rr.com:


I understand that the AGM cells in my boat are a wrapped sandwich of
glass mat and the lead plates. How can contact between these plates
be very likely? Is the boat just sitting there motionless more
likely to have these well supported plates bend than all those cars
sitting in unheated garages and out on the street? First, the
batteries have to discharge which seems pretty unlikely with the
cables disconnected. My wife has to have AAA jump start her car a
half dozen times a winter because she doesn't close the doors all the
way or leaves the lights on. No problem so far.



Oh, the cars have their share of battery explosions, usually from the
unfused alternator diodes shorting to ground or the frozen starter with
the shorted commutator. However, it's not much of a mess in a car where
the acid bath is so easily washed away as soon as it happens, and is,
mostly, forgotten, unless it exploded when the WIFE turned the key,
which, of course, is all YOUR fault. The batteries, usually, don't short
internally plate-to-plate because of the separator....as long as they
don't get hot when the supercharger screws up and puts 40A to them for a
couple of weeks while you're ashore or the boat alternator diodes that
ALWAYS have DC voltage on them with the key off, short same as the car.

I had a red AGM battery that came with my government-surplus Chevy diesel
stepvan "go off", by the way. That was an internal short. It didn't
explode, I suppose because the short wasn't a dead short. It simply
MELTED as the plates became so hot it blew the safety pressure valves out
of it and boiled the electrolyte in the gauze into steaming sulfuric
acid. The cell that shorted, took out all the other cells because it
melted from its cylinder into their cylinders. I swapped it with an AGM
dealer who gave me a nice credit against another AGM battery priced like
a Lexus front end. Luckily, the one that melted opened from post to post
so it didn't also short the other one in parallel with it used to crank
the 6.2L diesel V-8...which now runs on free frying oil from 3 chinese
restaurants...(c; (www.frybrid.com)

Larry
You ARE paying the state and federal road tax aren't you?

krj wrote in news:VUe1h.77602$zF5.2131
@bignews1.bellsouth.net:

You ARE paying the state and federal road tax aren't you?


Oh, sure.....Yeah.....right....

If they come and ask for it, nicely, without the guns.

Larry
--
I sure hope Halloween comes real soon....
I've run out of Halloween candy THREE TIMES SO FAR!