Samlex America MSK-10A - Manual (Page 18)

18 | SAMLEX AMERICA INC.
SeCtIOn 4 | Operation
batteries. As the battery is discharged and charged, concentration of Sulphuric Acid
becomes higher at the bottom of the cell and lower at the top of the cell. The low acid
concentration reduces capacity at the top of the plates, and the high acid concentration
accelerates corrosion at the bottom of the plates and shortens battery life. Stratifica-
tion can be minimized by the equalization Stage by raising the charging voltage so that
the 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 imbal-
ances prevent some cells from reaching full charge. As a battery is discharged, the cells
with lower voltage will be drained further than the cells at the higher voltage. When
recharged, the cells with the higher voltage will be fully charged before the cells with
the 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 (0.2 V or more) and
in the specific gravities (0.015 or more) of the individual cells, the cells will require equal-
ization. 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.
eQUALizAtion cHARGinG cYcLe
Please refer to fig 4.1b
equalization charging cycle is carried out automatically whenever the battery is over
discharged and the battery voltage drops to 11.1V for 12V battery and 22.2V for 24V
battery.
Stage 1 bulk Stage
This is the same as the bulk Stage in the Normal Charging Cycle.
Stage 2 equalization Stage
The controller enters this stage from the previous bulk Stage when the battery
voltage rises to the equalization Transition Voltage Set Point “Ve” which is internally
set as follows:
- “Ve” for 12V battery: Gel is not equalized / 14.6V for Sealed (AGM) / 14.8V for flooded
- “Ve” for 24V battery: Gel is not equalized / 29.2V for Sealed (AGM) / 29.6V for flooded
This stage is timed for 2 Hrs - either continuous or cumulative
This is a constant voltage stage and the Mosfet Switch operates under PWM control by
feeding pulsing Short Circuit Current “Isc” with constantly reducing Duty Cycle (< 100%
to > 0%) / average current to keep the battery voltage constant at the equalization
Transition Voltage Set Point “Ve”. This is an intentional, controlled over voltage condi-
tion for the battery for 2 Hrs. This is necessary for equalization requirements.
Change over to the next float Transition Voltage Set Point “Vf” (13.8V for 12V
battery and 27.6V for 24V battery) is possible only after the battery voltage is held at
the selected equalization Transition Voltage Set Point “Ve” for continuous or cumula-