LR3D Technical Manual
Section A
Rev. IR (5/13/2020)
Introduction
B&C Specialty Products
Page A - 3
bandc.com
turn of the potentiometer will adjust the voltage by approximately 0.2V on the LR3D-14 and
0.4V on the LR3D-28 (clockwise to increase, counterclockwise to decrease). The available
range of adjustment is approximately 11.0V-16.0V (LR3D-14) and 22.0V-32.0V (LR3D-28).
Use a handheld digital voltmeter at the battery to confirm any field adjustment.
In normal operation the Low-Voltage (LV) warning light will not be illuminated. The light may
flash in response to low engine RPM and high bus load, however; or it may flash to indicate an
emerging problem in the charging system.
The integrated Over-Voltage (OV) protection is set at a non-adjustable 16.25V (± 0.25V) on the
LR3D-14, and 32.5V (± 0.5V) on the LR3D-28. When triggered, this protective response will
cause the 5A field supply circuit breaker to open, thereby depriving the alternator of excitation
voltage and causing it to drop off-line. The alternator will remain off-line until power is restored
to the circuit by manually closing the 5A circuit breaker.
The LV warning light will begin to flash when the voltage sensed at terminal 3 drops to
approximately 12.7V and below (LR3D-14), or 25V and below (LR3D-28). The warning light
will cease flashing if/when the sensed voltage rises above these thresholds.
PARTS LIST
The following parts are supplied with the LR3D-14 and LR3D-28:
Qty. Part
No.
Description
1
LR3D-14 or LR3D-28
Alternator Controller (Regulator)
8
S814R6
Terminal, Ring, 18-22AWG
1
S888-1-4 (14v) or S888-2-4 (28v)
Warning Lamp, Yellow
The following parts may be needed but are
not
supplied:
Qty. Part
No.
Description
1
L-40, LX60, BC410-H, BC462-H (or equal)
Alternator
1
CB2
Circuit Breaker, 2A
1
CB5
Circuit Breaker, 5A
1 S700-2-3
Switch,
Toggle
NOTE
The pre-set charging voltage of the LR3D should be suitable for most
12V & 24V Sealed Lead Acid (SLA) batteries. Electrical systems
using legacy “Flooded” batteries, or Lithium (LiFePO
4
or similar)
batteries, may require field adjustment. Consult the documentation
provided by the manufacturer to ensure adequate battery performance
and service life.
