Copyright © 2007 BEP Marine Limited. All rights reserved. A product of New Zealand.
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VOLTAGE SENSITIVE RELAY
DUAL BATTERY CHARGING MADE EASY
Installation instructions
BEFORE INSTALLING
IMPORTANT
Do not use any type of corrosion inhibiting spray such as CRC,
INOX etc. on any part of this unit. These units are hermetically
sealed so do not require any other form of sealing. The studs have
been tinned to inhibit corrosion, use petroleum grease if required
(on metal parts only).
ENSURING CORRECT BATTERY SIZING:
The charging system must be correctly sized to
the batteries.
If the charging system is too small for the batteries
the VSR will not work properly.
How the VSR works
Once the starting battery’s voltage rises to above 3.7 VDC,
the VSR switches to charge both batteries in parallel, when the
voltage drops below 2.8 V DC the VSR disengages. A buzzer-
like sound can be heard as the relay quickly switches in and out.
Disengagement can occur at idle (low amps out due to slow speed
of alternator) or if the house battery is at a low charge. An increase
of the engine’s RPM will increase the alternator output and hold up
the voltage.
Alternator vs battery capacity
Alternator Size Second battery size
0 Amp
60 AH GRP 22
6 Amp
85 AH GRP 24
25-35 Amp
85-00 AH GRP 27
50-60 Amp
00-30 AH GRP 3
80-90 Amp
30-220 AH GRP 80
INSTALLATION
Connect the VSR to the back of the battery
isolating switches, ensuring that the battery cable
is correctly sized. This will ensure good current
flow to the battery, reducing unwanted voltage
drops to the VSR. The LED on the front of the
VSR should be visible, as it will instantly show
when it is in operation.
Note: When using a VSR in conjunction with a high performance
voltage regulator (eg Next Step Regulator) the regulator sense wire
must go to the same point as the sense for the VSR ie the start battery.
Remove base to expose studs and negative lead. Cut out cable
access slots:
) With a hacksaw blade, cut vertical lines
into the side walls of the VSR case, as shown
by dashed lines (approximate positions). Stop
cutting at the point where the plastic steps up
to a thicker wall. Take care not to damage the
circuit board with the blade.
2) Once the two slots have been cut, with a pair of pliers bend the
middle section (between the two slots) inwards until it snaps away
from the main body (Along horizontal dashed lines)
Use countersunk screws for
fastening base down.
Use Panhead screws for
fastening the VSR onto the base.
4
8
m
m
Base (side view)
Voltage
Sensitive
Relay
Panel
70
House Batt
Isolator
Negative
Bus Bar
70
Motor Batt
Isolator
Start
Battery
708-68.5
Link Bars
70
Emergency
Start
Isolator
708-68.5
Link Bars
House
Battery
–
+
–
+
ENGINE
BATTERY
NAV LIGHTS
POLE LIGHTS
CABINLIGHTS
COCKPIT LT
BILGE PUMP
SPARE
Engine
+
Panel
70
House Batt
Isolator
Negative
Bus Bar
Dual Sensing
Voltage Sensitive
Relay
70
Motor Batt
Isolator
Start
Battery
708-68.5
Link Bars
70
Emergency
Start Isolator
708-68.5
Link Bars
+
–
+
ENGINE
BATTERY
NAV LIGHTS
POLE LIGHTS
CABINLIGHTS
COCKPIT LT
BILGE PUMP
SPARE
Engine
House Battery
Isolator
Motor Batt
Isolator
S
E
C
O
N
D
B
A
TT
E
R
Y
P
O
S
IT
IV
E
+
S
E
N
S
E
B
A
TT
E
R
Y
P
O
S
IT
IV
E
+
Rear view
Wiring for Voltage Sensitive Relay
Wiring for Dual Sensing Voltage Sensitive Relay
VSR Rear view
(same with both installations)
Battery
Negative
Black mm
(Supplied)
68 mm
68
mm
