The key word here is "recombinant". The oxygen that was originally
bound to the hydrogen does not just cease to exist. The caps just
recombine what was in the battery to begin with. The catylist just
incourages them to join together. The process is slow and continuous so
there is no actual fire but it does produce heat. That is why you have
to remove the caps when equalizing. The gas is produced at a much
higher rate when equalizing so the reaction is faster and enough heat is
generated to melt the caps and the case around the fill holes.

The whole purpose of high performance charging systems with 3 stage
regulators is to get the maximum charge into the bank in the least
amount of time. Therefore it has to charge the bank at a rate very
close to the gassing point.

While antimony not used in Gel and AGM batteries it is still used in wet
cell batteries.

"No maintenance" batteries, more properly called Valve Regulated Lead
Acid are maintained under from 1 to 4 PSI The pressure encourages
recombination of most of the gasses but once the level drops to low they
are trash. They are OK for starting batteries that never get bulk
charged but suffer a quick and painfull death as deep cycles.

No question that AGMs are the future of lead acid batteries but right
now when it comes to total amps per dollar good old wet cell L16s and
golf cart batteries have them beat hands down.

BTW, you should read the links you posted. Everything I have said is
verified in them. :-)

Larry W4CSC wrote:
Does anyone know how this miracle works? How does hydrogen passing
platinum produce water at room temperature? Where does the oxygen
come from? Air vents out of the cell as soon as hydrogen displaces
it, leaving pure hydrogen.

Now let's look at batteries.......

Run down your deep cycle battery to 11 volts. Put the charger on at
10 or 20 A and wait 20 minutes for it to charge a while. Open up the
cells and look inside. Notice it's not "perking" away? Why?

A long time ago, lead plates in lead-acid batteries was supported by a
grid of antimony built into the plates. Lead is too soft to hold
itself up in thin sheets. During charging, the antimony reacted with
the water, splitting up the hydrogen and oxygen and causing the
hydrogen to vent out of the batteries in LARGE amounts, causing an
awful explosion hazard as it had to be vented out of the batteries.
WW2 subs had bad hydrogen problems in their battery compartments and
many died from the explosions.

Modern batteries no long use antimony to support the lead dioxide
plates. The alloys used now react much less and produce almost no
gas. (Notice the maintenance-free battery in your car? Why doesn't
it gas like hell and use lots of water?)

Great information is available on:
http://www.vonwentzel.net/Battery/00.Glossary/
http://www.flex.com/~kalepa/technotes.htm
http://www.4unique.com/battery/battery_tutorial.htm
http://www.ctts.nrel.gov/BTM/pdfs/evs_17paper.pdf

Most of the outgassing is caused by CHARGING TOO FAST...charging it
faster than it can chemically react. Charge them as slow as you
can.....with the latest pulse technology is nice, too!

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
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