Specialty Concepts SC3/20 - Manual (Page 13)

C H A R G E S E T - P O I N T A D J U S T M E N T
CHARGE SET-POINT ADJUSTMENT SHOULD BE ATTEMPTED ONLY BY QUALIFIED PERSONNEL.
IMPROPER CALIBRATION CAN RESULT IN BATTERY AND EQUIPMENT DAMAGE.
The standard charging set-points of the SC3/20 will be proper for a majority of the applications, however the
SC3/20 allows field adjustment of charging set-points. Caution should be used, and calibration should not be
attempted if there is any doubt about the procedure or ultimate set-points required. The controller can be returned
to the factory or authorized representative for calibration at any time.
WHEN RE-CALIBRATION IS RECOMMENDED: The standard charge cutoff set-point for the SC3/20 is 14.3
volts. Adjusting the charge set-points is recommended for certain situations which might otherwise result in
under or over charging the batteries. These recommendations are approximate and can be influenced by
specific conditions. Contact the battery manufacturer or supplier to verify proper settings.
SOME BATTERIES REQUIRE DIFFERENT CHARGING VOLTAGES: Sealed, maintenance free batteries
may require a lower charging voltage. Generally, for these batteries, the controller should be set for 14.1
to 14.3 volts.
WHEN THE BATTERY WILL BE SEEING PROLONGED TEMPERATURE EXTREMES: During prolonged
temperature extremes (when the battery will be exposed to average temperatures below 50
°
F (10
°
C ) or
above 90
°
F (32
°
C) for weeks at a time), the set-point should be raised .3 volts (14.6) for lower
temperatures and lowered .3 volts (14.1 volts) for high temperatures.
IN SYSTEMS WITH EITHER EXTREMELY HIGH OR LOW CHARGE RATES: Systems with very low
charge rates (1 amp per 100 amp hour of battery) should have the set-points lowered to about 14.0 to
14.2 volts and systems with very high charge rates (over 20 amps per 100 amp hours of battery) should
increase the charging set-point to 14.8 to 15.0 volts.
PROCEDURE - All adjustments should be made at times of mild room temperature. At cool or warm times, the
display reading will stray somewhat from the actual voltage set-point. To calibrate the SC3/20, proceed as
follows.
1. COMPLETE BATTERY CONNECTION - Connect the battery to the SC3/20 according to the normal
installation instructions. The array may be connected or not, as desired. The SC3/20 can be calibrated after
normal installation.
2. SET FRONT SWITCH TO “C” - Move the metering switch selector to the “C- CHARGE SET-POINT” position.
3. LOCATE ADJUSTMENT POT - There are three adjustment trimpots, the small, square, components with a
slotted circle in the middle, located on the back of the controller on the left side of the charge control board
(the one with the red/yellow/green LED’s). The lowest of the three is the trimpot that adjusts the charging set-
points of the controller. (Refer to FIGURE 4 - BACK VIEW)
4. DETERMINE NEW VOLTAGE SET-POINT - Decide on a new voltage termination set-point. Note that
changing the termination set-point will also change the "charge resumption" set-point by an equal amount.
Do not set the controller for more than 16.5, or less than 13.5 volts. When calibrating above 15.0 volts, check
to see what the operating limits of other equipment may be, as some electrical equipment (fluorescent lights,
inverter) may be damaged or not operate at voltages over 15 volts.
CAUTION: DO NOT calibrate the SC3/20 for a voltage in excess of 16.5 volts, as this can damage the
controller.
5. ADJUST POT - Turning the trimpot counter-clockwise increases the set-point, clockwise decreases it.
CAUTION: This is a 270 degree trimpot. Do not turn the trimpot past the endstops, as this can disable the
controller.
A small amount of rotation results in a large change in the set-point, and it is possible to adjust the set-points
to an improper operating level. Carefully adjust the trimpot to change the voltage reading to the desired
setting. The display will read a negative number, and will be in tenths of a volt, so a setting of 14.1 will be
displayed as -141. It may require several attempts to set the trimpot to the desired setting.
Example: Charge Set-point Monitor Reading at Position C (at room temp.)
14.1 volts - 141
14.3 volts (factory set) - 143
14.6 volts - 146