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battery is fully recharged. However, a solar battery is seldom completely recharged, so the
soft lead sulfate crystals harden over a period of time. Only a long controlled overcharge, or
equalization, at a higher voltage can reverse the hardening sulfate crystals.
In addition to slowing or preventing lead sulfation, there are also other benefits from
equalizations of the solar system battery. These include:
Balance the individual cell voltages.
Over time, individual cell voltages can drift apart due to slight differences in the cells. For
example, in a 12 cell (24V) battery, one cell is less efficient in recharging to a final battery
voltage of 28.8 volts (2.4 V/c). Over time, that cell only reaches 1.85 volts, while the other
11 cells charge to 2.45 volts per cell. The overall battery voltage is 28.8V, but the individual
cells are higher or lower due to cell drift. Equalization cycles help to bring all the cells to
the same voltage.
Mix the electrolyte.
In flooded batteries, especially tall cells, the heavier acid will fall to the bottom of the cell
over time. This stratification of the electrolyte causes loss of capacity and corrosion of the
lower portion of the plates. Gassing of the electrolyte from a controlled overcharging
(equalization) will stir and remix the acid into the battery electrolyte.
NOTE: Excessive overcharging and gassing too vigorously can damage the battery
plates and cause shedding of active material from the plates. An equalization that is
too high or for too long can be damaging. Review the requirements for the particular
battery being used in your system.
4.4.1 Standard Equalization Programs
Both automatic and manual equalizations can be performed using either the
standard charging programs or a custom setting.
Manual Equalization
The SunStar is shipped with the DIP switch set for manual equalization only. This is to
avoid an unexpected or unwanted automatic equalization. In the manual mode, the
pushbutton is used to both start or stop a manual equalization. Hold the pushbutton down
for 5 seconds to start or stop an equalization (depending on whether an equalization is in
progress or not).
There are no limits to how many times the pushbutton can be used to start and stop
equalizations. Equalizations will be terminated automatically per the charging program
selected if the pushbutton is not used to manually stop the equalization.
Automatic Equalization
If the equalization DIP switch is moved to the ON position
)
, the equalizations will begin
automatically per the charging program selected. Other than starting, the automatic and
manual equalizations are the same and follow the standard charging program selected. The
pushbutton can be used to start and stop equalizations in both the manual and automatic
