©
2017 Sensata Technologies
Page 64
Operation
4.4.1
Equalizing the Battery Bank
Equalizing (EQ) is a “controlled overcharge” of a lead-acid battery (or battery bank) done to help
the battery reach and maintain peak capacity. This controlled overcharging helps equalize the
chemistry in the individual battery cells by mixing the battery electrolyte (to reverse the buildup
of strati
fi
cation), and by removing lead sulfate that may have built up on the plates. These
conditions if left unchecked, reduce the overall capacity of the battery.
WARNING
: Do not perform an equalization charge without reading and following all
safety precautions pertaining to charging/equalization. Carefully review all information
in this manual and that provided by the battery manufacturer, and any equalization
information for any other charger in the system (i.e., inverter owner’s manual).
WARNING
: Equalizing produces hydrogen and oxygen gas. To avoid explosions, ensure
the battery compartment has adequate ventilation in order to dissipate this gas.
CAUTION:
Precautions and Guidelines when Equalize Charging:
• If any DC Loads are connected to the battery bank, ensure they will not be damaged
by the higher voltage applied to the batteries during the equalize charge. If in doubt,
disconnect the loads to prevent damage.
• Ensure your batteries can be equalized. Only do so if permitted by your battery
manufacturer or dealer. Performing an equalization charge on batteries other than
liquid lead acid or certain AGM types could cause permanent damage.
• Check all batteries before and after equalization and make sure the electrolyte is at
the correct level. During the equalize charge, the batteries will begin gassing and
bubbling vigorously, which consumes water. So prior to equalizing, ensure each cell
has adequate distilled water, but do not over
fi
ll because the electrolyte may expand
and over
fl
ow. Once the equalization charge cycle has
fi
nished, add water as needed
to ensure the plates are covered.
• Refer to your battery manufacturer to either leave the
fi
ller caps screwed on (if
vented), leave them on loosely, or remove them and cover the opened cell tops with
a folded paper towel.
• Only equalize when you are present to monitor the batteries during the entire
charging cycle.
How often should I equalize charge?
Some experts recommend to equalize batteries every
thirty days when they are cycled daily, or every thirty deep cycles. Other experts only recommend
equalizing when the battery capacity has decreased (i.e., not holding loads as well now as they did
previously), the cells have a low speci
fi
c gravity, or when the difference between any individual
cell has a speci
fi
c gravity reading greater than .015 after being fully charged. Contact your
battery manufacturer for their recommendations.
How long should I equalize charge?
While the batteries are gassing, monitor the speci
fi
c
gravity readings every hour. When the speci
fi
c gravity readings no longer increase, the equalization
charge is complete and should be stopped manually. If you do not stop the equalization process
manually, the EQ cycle ends automatically after the EQ time is complete and goes into the Float
charge mode (FLOAT LED comes on).
Info:
When con
fi
gured as a standalone device, and Flooded or AGM 1 is selected as
the Battery Type, the EQ time is 4 hours at the EQ voltage. However, the PT controller
will be in the EQ charge mode longer than four hours if conditions prevent the PV array
from producing enough power for the PT controller to maintain the batteries at the EQ
voltage level.
Info:
Equalization charging time
:
a) Counts when EQ is enabled and the battery voltage
is close to the EQ Volts setting (
≤
0.1v/12-volt systems,
≤
0.2v/24-volt systems, or
≤
0.4v/48-volt systems); b) Pauses when controller is turned off (using a remote);
c) Clears when EQ charge mode time is completed, the controller is forced into Bulk/
Absorb or Float (using a remote), or the EQ charge mode is manually stopped.
