Is the 787 a failure ?

On Fri, 22 Mar 2013 17:50:57 -0600, Daryl
wrote:

On 3/22/2013 4:16 PM, wrote:
On Fri, 22 Mar 2013 15:16:58 -0600, Daryl
wrote:

On 3/22/2013 2:59 PM, Jim Wilkins wrote:
wrote in message
...

VERY common problem on "A Piece of Crap" UPS systems (as well as
some
cheaper ones) but when they split they don't leak.

The acid in an AGM battery is Absorbed in the Glass Mat.
jsw



No, the Glass Matt just keeps it from sloshing around. You break open
that case and the solution will leak out post haste.

And you have NEVER seen an accidental leaking of an AGM battery. Now
just admit it.

Those that can: Do. Those that can't: Teach

Daryl

They are also called "starved electrolyte" batteries - and even when
fractured they do not "leak". They are very similar in that respect to
the older "gell cell"


Totally different internal makeup between the two. Like many, you are
confusing the two and thinking the internal makeup is similar. They aren't.

I'm not confusing them. I know the difference - and I have some
experience with both gel and AGM batteries in UPS units over a 20 year
history, as well as flooded cell deep discharge batteries in EV use -
going back that far as well, plus "gel" experience in wheelchair
batteries and the old "cyclons"

I have yet to see fluid leak from an AGM battery but I'll admit I've
never smashed a good fresh one. Smashed a few dead ones - and they
are just "damp" "starved electrolyte" batteries have a fiberglass mat
of almost felt consistency which is wet with acid to about 95%
capacity - so if the case is broken there is NO free electrolyte to
leak out.

This is why they are not considered hazardous and do not require
hazardous labeling, and can be shipped by air.

The AGM must be kept upright since it does have free liquid in it.

Baloney. A valve regulated recombinent gas absorbed electrolyte
battery can be mounted, charged, and discharged in any position.
What
you see when it's case is bulged is from the Hydrogen and Oxygen being
unable to be vented due to excessive overcharging or the vent hole is
plugged up. Like the old style Lead Acid, when it vents, it burns off
the H2O breaking it up to Hydrogen and Oxygen Gasses. When you open one
up that has done this, what is left is the other parts of the liquid in
the form of solids or actually, powder. The Plates are still lead.

Wrong. In an AGM (recombinent gas absorbed electrolyte) battery the
oxygen and hydrogen are catalytically recombined and never vented
under normal conditions. In extreme overcharge, water vapout pressure
can bulge the case if the valves don't vent and the battery boils dry
- which can also bulge the case. You might use a lot of the batteries,
but you don't understand them very well.
This one, like the unsealed lead acids can form Sulphates on the plates
which shorten the life of the battery because of running them below 50%.
The good news is the desulphators work offered with low amperage may
recover them to almost new condition when that happens.


And AGM batteries are virtually imune to sulphation
When you need a battery that cannot be kept in an upright position, you
choose the Gel Cel. In this battery, the Sulfuric Acid is mixed with
Silica Fume and it makes it into a gel. The Plates are of a Calcium
makeup and are not lead.
Again, Baloney. They are calcium doped lead.

The calcium is used in gell and flooded acid batteries to harden the
lead and strengthen the plate without the excessive gassing and
corrosion, and self discharge of the 3% antimony alloy of a
"conventional" battery. Some batteries use a "conventional" positive
and a calcium negative grid - with the lead paste and lead sulphate
paste caked to the grid, and some use calcium alloy grids for both
(more expensive). A calcium/calcium battery does not gas much and is
used in sealed recombinent (maintenance free) batteries.

With AGM the plates are supported by the glass mat, and in many cases
no calcium or antimony is required. Pure lead thin film AGM batteries
are state of the art for telecom and medical equipment use. They give
the highest power density per unit volume of any lead based battery
technology. They will beat any gel battery hands down - but they do
not come cheap. They can put out insane current, and can be fast
charged without damage.
Odyssey batteries are thin plate pure lead AGM batteries.

We use them in recreation aircraft use almost exclusively.

People confuse the AGM with the Gel Cel all
the time. If you want the best, longest lasting UPS battery, get rid of
the AGM and go with the Gel Cel. They cost more but last much longer.

An AGM battery can stand much higher charge and discharge than the
rather fragile and fussy Gel Cell, which is why gell cells are
virtually extinct in small to medium UPS units and MOST other
applications. Gell and flooded acid batteries both require about 115%
of their rated output in charge - ie - a 100 ah battery requires 115ah
of charge (when new - they can get as bad as 125% and still function).
AGM batteries are down around 102%. This means a LOT less heat in AGM
applications compared to gel. (all that extra wasted 13% power is shed
as heat)

For long slow discharge, in a device with the proper charge controller
for Gel use, the Gel is still a (reasonably) good solution. For heavy
loads, not so good. For high charge rates, not so good. For mobile
high vibration use, not so good - and they DO require a specially
programmed charger. Do NOT charge gel batteries with a normal flooded
acid or agm charger. A pure lead AGM battery is almost always a
better choice.

wrote in message
...

For long slow discharge, in a device with the proper charge
controller
for Gel use, the Gel is still a (reasonably) good solution. For
heavy
loads, not so good. For high charge rates, not so good. For mobile
high vibration use, not so good - and they DO require a specially
programmed charger. Do NOT charge gel batteries with a normal
flooded
acid or agm charger. A pure lead AGM battery is almost always a
better choice.

Good advice.

While searching for a comparison of flooded, AGM and gel float
voltages I found this:
http://www.windsun.com/Batteries/Battery_FAQ.htm

I charge all types except NiCd and NiMH with a lab supply, and use it
to temporarily recover old NiCd tool packs that have dropped to zero
and won't charge on an automatic charger, and to reform old
electrolytics.

Lead-acids reveal their state of charge by the increasing voltage
needed to force a constant current into them. I get the endpoint
topping or float voltage from the maker's data sheet, or for flooded
cells by measuring the specific gravity and watching for bubbles in
all cells.

I've noticed that the fully charged and endpoint voltages are about
0.2V different for two identical SLA31 batteries bought a year apart.
The cause could be manufacturing differences in the plates, or
variations in the volume or concentration of the acid.
jsw