28 | SAMLEX AMERICA INC.
Termination of Equalization Stage in Manual Mode Before Completion: If the unit
is set for manual Start / Stop of Equalization Stage (Using DIP Switch No. 5) and
equalization is switched ON but is switched OFF before completion, the charger reverts
to “Bulk Stage” and undergoes Normal Charging Algorithm explained above.
Temperature Compensation During Charging
The temperature of the battery electrolyte affects the rate of chemical reactions in
the batteries as well as the rate of diffusion and the resistivity of the electrolyte.
Therefore, the charging characteristics of the battery will vary with temperature. This
is nearly linear and the Voltage Coefficient of Temperature Change is normally taken
as -3 mV to -5 mV / ºC / Cell. Please note that the Voltage Coefficient of Temperature
Change is negative which means that as the temperature rises, the charging voltage is
required to be reduced and as the temperature is decreased, the charging voltage has
to be increased.
All charging voltage set points are normally specified at 25ºC / 77ºF. In PV systems,
battery temperatures often vary up to 15ºC from the 25ºC reference. The Absorption,
Float & Equalization Voltages must then be adjusted, or a controller with Temperature
Sensor should be used. Table 3.4 on page 12 shows example of adjustments for
Absorption Voltage of say 14.4V for 12V battery (based on Voltage Coefficient of
Temperature Change as -5 mV / ºC / Cell or -30mV (.03V) for a 6 cell, 12V battery).
In case temperature compensation is not provided, the warmer battery at 40ºC will
begin to heat and outgas at 13.95V and will continue to overcharge until the non-
compensated Absorption Voltage set point is reached (14.4V). In cooler temperatures,
the 10ºC battery will experience severe undercharging resulting in sulfation.
The controller has provision for temperature compensation with the help of
Temperature Sensor. This Temperature Sensor is required to be connected to the
terminals marked BTS+ and BTS- (Fig 5.2).
It is recommended that the above Temperature Sensor may be used if the battery
electrolyte temperature varies more than 5ºC to 10ºC (9ºF to 18ºF) from the reference
temperature of 25ºC (77ºF).
SECTION 4 |
Principle of Operation & Features
Summary of Contents for samlexpower SCC-30AB
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