LT-12PREG-1
9
Charles Industries, Ltd. All rights reserved. Printed in the United States of America.
Each input is described in detail in the following paragraphs.
ABS Input
When this input is connected, the alternator regulator is held at the absorption setpoint. Removal of the input sig-
nal causes the alternator regulator to begin stepping towards the float voltage. Step-to-float is an intermediate
mode where the float setpoint is approached in small steps over time. This is done in an attempt to maintain
some alternator output and keep the tachometer alive.
LOCK Input
This input locks the alternator regulator at the gassing setpoint, which is halfway between the absorption and the
float setpoint. Removal of the signal toggles between stepping to float or going to the absorption setpoint. The
first time the signal is removed, the alternator regulator steps to float. The next time the signal is asserted, the
regulator will go to the absorption setpoint. The LOCK input can be used to completely control the setpoint.
Current Limiting (LIM & EQL)
Two potentiometers with two input signals permit duty cycle current limiting at two specific setpoints. Duty cycle
current limiting is a mode in which the maximum amount of time that the alternator is driving the field is set by the
potentiometer. Current limiting is useful to reduce alternator output, reducing horsepower requirements from the
engine.
Two settings are available (LIM and EQL). EQL overrides the LIM input. For normal limiting on a small engine,
use the LIM input. The EQL input can be connected to the same switch that enables another load on the engine.
For instance, a clutch-driven pump may require a further reduction in current; in that case, wire the EQL input to
the switch that activates the clutch for the water pump. The potentiometer for LIM is R11. R12 sets the current
limit for the EQL input.
Equalization
Equalization is a process in which the voltage on the battery is allowed to rise to to a higher voltage, typically
16.2/32.4 volts for most batteries; applied current is limited to 3–7% of the Ah capacity of the battery. The applied
current must be set using R12.
The EQL input is used for a second current limit whenever the input signal is activated. To enter actual equaliza-
tion mode, the two pins of P1 must first be shorted with a jumper terminal or a switch connected to the two pins
(refer to Figure 1). This changes the mode of the EQL input signal to regulate at the equalization voltage set-
points, as well as current limit. Then the EQL limit should be activated for at least 2 seconds, then released. To
terminate the equalization process, activate the limit a second time. Equalization terminates automatically when-
ever the ending voltage or time is achieved.
Note:
Equalization produces a higher voltage than some normal equipment can tolerate. Turn off equipment
that will not tolerate an input of 17 volts or more.
The alternator regulator does not permit equalization for the gel batteries selected by S1.