littelfuse if 156 48510 lvd instruction guide
Automatic Low Voltage
Disconnect Switch 48510
200A 12V DC
Connection Schematic
c. Connect orange “Run” wire to the ignition
switch (Ign/Run position).
d. Unused wires should be capped or otherwise
insulated from active circuitry.
4. Connect LVD “Battery+” stud to the battery
positive terminal (or battery positive terminal
block) using appropriate heavy gauge cable and
proper fusing.
NOTE: If a master disconnect switch is used, the
LVD should be installed “after” the master
disconnect, such that the master disconnect
switch can be used to shut off power to the LVD.
5. Reconnect the battery or power supply.
Normal Operation Summary
Disconnect the battery or power supply or switch
it off with the master disconnect switch before
1. Connect black “Ground” wire to ground.
2. Connect Low Voltage Disconnect (LVD) “Load+”
stud to accessory loads using appropriate heavy
gauge cable.
3. Optional circuit connections:
a. Connect violet “Manual” wire to a normally
open momentary switch. Connect the other side
of the switch to +12V.
b. Connect white “Alarm” wire to a 12V, 50mA
audio/visual alarm. Connect the other side of
the alarm +12V.
1. When the voltage is above 13.0V for 10
seconds, the LVD will automatically connect the
loads to the battery.
2. When the voltage drops below 12.1V for 60
seconds, the Alarm will signal, warning the user
that the loads are about to be disconnected.
a. The user has the option to override the
imminent disconnect by asserting the Manual
signal (see below).
b. It should be noted that the alarm can be
audio, visual or both.
c. After 60 seconds of the alarm, the loads and
the alarm will be disconnected.
Additional Operating Details
1. Connection Check – Upon power-up, the LVD
initially checks to ensure proper cabling,
specifically the Battery+ and Load+ connections. If
improper cabling is detected, the LVD will
activate the alarm until the user corrects the
2. Manual Override
The Manual signal is asserted when the user
connects the violet wire to +12V for 1 second. This
is normally accomplished with a momentary
switch. The Manual signal serves several functions,
depending on when it is activated. At any given
time, it can be used to toggle the loads on or off.
It can also be used to override the automatic
a. While the Alarm is signaling, activating the
Manual signal will override the imminent
disconnect, thereby keeping the loads on for an
additional 60 minutes. After the 60 minute time
period, the LVD will resume its normal
General Specifications
-40ºC to 85ºC. SAE J1455 & J1113
Electronics sealed to IP67
Ignition-proof to ISO 8846
200A continuous. Inrush: 500A (for 5 seconds).
2mA max quiescent current
Less than 12.1V for 2 minutes.
Factory programmable.
Accuracy ±100mV
Active low, 50mA
Activates 1 minute before disconnect.
Overall height is 3.0” (760mm)
Dimensions are in inches (mm)
Submit all technical questions to:
[email protected]
b. If the user activates the Manual signal to turn
the loads off, the loads will remain off until the
user re-activates the Manual signal, thereby
turning the loads back on. This is often used
when storing a vehicle for a long period of time.
c. If the LVD has disconnected the loads (due to
low voltage) and the Manual signal is asserted,
the loads will be toggled “on” regardless of the
voltage. After 60 minutes, the LVD will resume
its normal operation.
3. Run Override
The Run signal is asserted when the user connects
the Run wire to +12V, usually via the IGN/RUN
position of the ignition switch.
a. If the Run signal is asserted, the loads will
not be disconnected, regardless of the battery
b. Asserting the RUN signal does not
automatically connect the loads as it may be
undesirable to draw high current before starting
a vehicle.
4. Overcurrent Shutoff
When the output current exceeds the preset
threshold of ~250A for 5 seconds (200A model),
the loads are disconnected and the alarm is
activated. The user must assert the Manual signal
to turn off the alarm and to reset the LVD to
normal operation. The overcurrent threshold for
the 150A model is ~190A.
Cole Hersee Co
rev 00
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