L-16 "cycling" requirements? [RE-wrenches]

[Bruce Geddes]

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Darryl,
            My understanding is that Antimony is added to alloy the lead and
help prolong grid life under the mechanical flexing that deep discharge
causes.  That is why standby batteries are pure lead grid and will last a
long time when floated but fail rapidly if deep cycled.

Antimony also increases the amount of gassing by lowering the gassing point
voltage.

Now that we are seeing tubular positive plate traction cells with polyprop
socks to support the pos grid, there is a move to 0% Antimony grids hence
less gassing and lower water consumption.

Based on my use of traction cells off-grid and the amount of water they
consume, this means my customers should be expecting to water once per year.

It is always the positive plate that causes the problems, again I am told it
is because the pos plate undergoes oxidation in the reaction and also there
are more negative plates in the cell so they never get pushed quite as hard
as the positive.  This is because you need to cover the ends of the cell to
get both sides of the positive plates reacting - hence the odd number of
negative plates so there will always be one more.  I guess pos plates are
more expensive to manufacture so they want the most out of them.

Some of the comments about "blowing sulphate crystals off the plate" miss
the point.  Sulphate is reacted acid and plate material.  Blow it off and
you lose those sulphate ions and also the plate material that is dislodged.
This will expose fresh plate surface to react and restore some performance
but it will still not be as good as a batttery that is Eq'd so sulphate does
not harden.  Proper Eq will cause those sulphate crystals to de-form and
return to lead compound and acid ions, not just dislodge.

Bruce Geddes
PowerOn


----- Original Message ----- 
From: "Darryl Thayer" <daryl_solar at yahoo.com>
To: <RE-wrenches at topica.com>
Sent: Sunday, May 22, 2005 1:36 AM
Subject: Re: L-16 "cycling" requirements? [RE-wrenches]


Question:
I was told that antinmony was added to the plates to
make them stronger to take vibration which fork lifts
and floor scrubbers might get. But RE systems should
not get.  I also believe the antinmony causes the high
self discharge rates.  So would not Lead calcium with
much lower self discharge rates and less need cycling
be better?




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