The shunt must be placed between the negative terminal on Battery 1 and
the main negative bus. All loads and charge sources should have their
negative terminals on the main negative bus, with the exception of the VSM
422 negative source which must be connected directly to the battery side of
the shunt. Shunt sense wires must be a twisted pair from shunt to VSM 422
for proper calculation of State of Charge (SOC). Twisted pair wire can be
purchased from electrical supply companies, or made by twisting by hand
or with an electric drill motor. The current reading for Battery 1 when it is not
being charged and has a load should be negative. If it is not, reverse the DC
shunt leads. (see page 95)
Voltage lines to the VSM 422 should be directly connected to the positive
battery terminal with a dedicated wire ahead of any other connections. This
will ensure correct voltage and SOC monitoring. Use an appropriate in-line
fuse (5A suggested) on the positive wire.
In most cases the AC Current Transformer should be located on the main
AC feed before any other devices. See http://bluesea.com/viewresource/86
for more information on AC Current Transformer location. The location does
not affect state of charge (SOC) calculations.
The Current Transformer does not indicate polarity. If AC voltage is applied
and current shows greater than zero but the power reading is zero or a
negative value, reverse the AC Current Transformer leads. The leads should
be twisted to reduce the effects of interference.
The ungrounded AC line should be fused inline with a fast acting fuse of
0.25A to 0.5A to protect against shorts.
Connect ?switch on? lead of bilge pump to the VSM 422 unit. This wire
should read +12/24V when running and 0V when off.
The battery temperature sensor should be located near the State of Charge
battery. It can be mounted to a battery box using the hole, or cable-tied to
the negative battery terminal. IMPORTANT! Do not fasten the Temperature
Sensor directly to the battery in any way that may puncture or damage
The VSM 422 is compatible with three sender protocols.
Resistive 2 Wire Senders: (see page 94 for Installation Diagram)
10 ? 180 Ohm VDO?Typical of Europe
240 ? 33 Ohm Teleflex?North America
Ultrasonic 3 Wire Senders: (see page 94 for Installation Diagram)
Blue Sea Systems PN 1810 and PN 1811.
Blue Sea Systems ultrasonic sender PN 1810 is used for water, waste, and
diesel fuel tanks up to 32" (812mm) in depth. Blue Sea Systems ultrasonic
sender PN 1811 is used for gasoline tanks up to 24" (609mm) in depth.
When connecting the tank sender to ground it is important to connect them
as directly as possible to the main negative bus to prevent high loads such
as battery chargers from affecting the tank readings.
The VSM 422 will not produce accurate readings if a second gauge is
connected to the same tank sender. Install a sender for each gauge if you
wish to read a tank level from more than one location.
The Blue Sea Systems ultrasonic sender requires an external power source.
When power to the sender is lost, the VSM 422 will read the tank as full, and
may trigger the tank?s high level alarm.
For each tank the sender must be specified, and the shape of the tank
set as rectangular or auto-calibrated before accurate readings are displayed.