MK Battery Manual

10
Why can’t VRLA batteries be opened?
VRLA (Valve-Regulated Lead-Acid) batteries, sometimes called SLA
(Sealed Lead-Acid) batteries or SVR (Sealed Valve-Regulated)
batteries work on a recombination principle. Oxygen gas is pro-
duced at the positive plates during charge. The charged negative
plates react first with this oxygen and subsequently with the elec-
trolyte. Water is produced and the negative plates are very slightly
discharged. Additional charging recharges the negative plates
instead of producing hydrogen gas. Since very little hydrogen and
oxygen is lost and the water (H
2
O) is retained, we say that the
gasses have recombined. To work properly, the oxygen produced
must be retained in the battery until the reaction is completed.
Positive pressure allows the gas to be retained.
If any VRLA (gelled or absorbed electrolyte) battery is overcharged,
gas will be vented from the valves. Hydrogen as well as oxygen will
be released. If continued, the electrolyte will eventually dry out and
the battery will fail prematurely. This is why charging limits are so
critical.
In a sealed battery a balance is maintained between the hydrogen,
oxygen and charge. If a VRLA battery is opened, or leaks, the nega-
tive plates are exposed to extra oxygen from the atmosphere.
This excess oxygen upsets the balance. The negative plates become
discharged. The positive plates may be subsequently severely over-
charged. The battery
will
fail prematurely, and the warranty will be
voided.
Some say calcium grids don’t do well in
flooded deep cycle applications. Why does
East Penn use calcium grids in VRLA
batteries for deep cycle applications?
Flooded calcium alloy makes a very efficient, low resistance battery.
Therefore, when deeply discharged, the plates release all their avail-
able power, eventually causing plate shedding and active material
fall-out. In contrast, with flooded antimony batteries, the antimony
helps lock the active material onto the grid. Therefore, the plate
does not shed as easily, which extends the deep cycle life of the
battery when compared to flooded calcium.
Our VRLA calcium alloy battery (East Penn’s exclusive patented
alloy) is also very efficient with low resistance. However, when
deeply discharged, the electrolyte is used up before the plates
are totally discharged because the battery is “acid-starved.”
This feature:
• limits the discharge the plates can deliver.
• protects the plates from shedding due to deep discharge.
• extends the life of the battery.
Why do EPM VRLA batteries have
longer cycle life than others?
Some of the major features that contribute to our long cycle life are:
• Our patented calcium/copper grid alloy delivers superior
performance due to the purity of the lead. Copper is added
as a “grain refiner.” This means that the microscopic grains
in our lead grids are odd-shaped, so they retard corrosion
and extend the life of our grid.
• Our thicker grids have more corrosion resistance than
thinner grids.
• Our VRLA batteries are protected against deep discharge
because they are “acid-starved.” This means that the battery
uses the power in the acid before it uses the power in the plates.
Therefore, the plates are never subjected to
destructive ultra-deep discharges.
• With proper temperature-sensing, voltage-regulated
charging (refer to table on page 11) the VRLA battery
never runs out of water.
• Our gel batteries contain ultra-premium, glass-mat,
dual-insulating separators which will not break down in
service. The glass mat embeds itself into the plate, which
retards life-shortening shedding.
• Our gel batteries contain polyester element wrap which retards
“mossing” or active material growth that causes short circuits.
• Our AGM batteries contain separators at the ideal compression
and ideal saturation to achieve the best balance between capaci-
ty utilization and recombination efficiency.
• Over 250 quality control checks assure superior performance
and long battery life.
Why do EPM VRLA batteries have
longer shelf life?
Our calcium/copper lead alloy premium separators and demineralized
electrolyte are ultra-pure. Impurities in the lead alloy, separators
and electrolyte cause tiny currents inside a cell which eventually
discharge the battery and shorten its shelf life. The purer the
components, the longer the shelf life. No one can match
East Penn’s purity!
Our exclusive “weld seal gasket” blocks the minute cell-to-cell
currents that cause self-discharge. The better the weld seal, the
longer the shelf life. Weld seals are exclusive to East Penn VRLA
batteries.
Does depth of discharge affect cycle life?
Yes! The harder any battery has to work, the sooner it will fail.
* You may experience longer or shorter life based upon application, charging regimen,
temperature, rest periods, type of equipment, age of battery, etc.
As you can see, the shallower the average discharge, the longer
the life. This is why it’s important to size a battery system to
deliver at least twice the average power required, to assure shallow
discharges.
Typical* VRLA Battery Cycling Ability
vs. Depth of Discharge
Typical Life Cycles
Capacity Withdrawn Gel AGM
100% 450 200
80% 600 250
50% 1000 500
25% 2100 1200
10% 5700 3200