Samlex Solar SCC-30AB Owner's Manual page 28

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PRINCIPLE OF OPERATION & FEATuREs
and formation of more Lead Sulfate crystals. Voltages drop on discharging results in
overheating and excessive voltage drop in the terminal voltage of the battery. Overall,
this results in poor performance of the battery. Sulfation may be reduced partially by
the stirring / mixing action of the electrolyte due to gassing and bubbling because of
intentional overcharging during the Equalization Stage.
Electrolyte Stratification: Electrolyte stratification can occur in all types of flooded
batteries. As the battery is discharged and charged, the concentration of Sulphuric
Acid becomes higher at the bottom of the cell and lower at the top of the cell.
Low acid concentration reduces capacity at the top of the plates, and high acid
concentration accelerates corrosion at the bottom of the plates and shortens battery
life. Stratification can be minimized through the Equalization Stage by raising the
charging voltage during this stage so that increased gassing and bubbling agitates /
stirs the electrolyte and ensures that the electrolyte has uniform concentration from
top to bottom. The stirring action also helps to break up any Lead Sulfate crystals,
which may remain after normal charging.
Unequal Charging of Cells: During normal charging, temperature and chemical
imbalances prevent some cells from reaching full charge. As the battery is discharged,
the cells with lower voltage will be drained further than the cells at higher voltage.
When recharged, the cells with higher voltage will be fully charged before the cells
with lower voltage. The more a battery is cycled, the more cell voltage separation
takes place. In a healthy battery, all the individual cells will have the same voltage and
same specific gravity. If there is a substantial difference in the cell voltages (0.2V or
more) and in the specific gravities (0.015 or more) of the individual cells, the cells will
require equalization. Equalizing batteries helps to bring all the cells of a battery to
the same voltage. During the Equalization Stage, fully charged cells will dissipate the
charging energy by gassing while incompletely charged cells continue to charge.
When to Equalize: The ideal frequency of equalizations depends on the battery
type (Lead Calcium, Lead-Antimony, etc.), the depth of discharging, battery age,
temperature, and other factors. One very broad guide is to equalize flooded batteries
every 1 to 3 months or every 5 to 10 deep discharges. Some batteries, such as the L-16
group, will need more frequent equalizations. The difference between the highest
cell and lowest cell in a battery can also indicate the need for equalization. The
battery manufacturer can recommend the Specific Gravity or voltage values for your
particular battery. Normally, if the cell voltage differential is > 0.2V, equalization may
be necessary.
Equalization Charging Algorithm
Equalization is carried out either automatically after every 28 days or manually when
desired. Equalization Voltage Regulation Sets Points and Equalization Time / Interval
will depend upon the type of battery being charged and can be programmed with the
help of DIP Switches 2,3,4 located at the back of the unit (Fig 5.2). Voltage regulation
Set Points will depend upon the type of battery being charged. This information is
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