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
Dual battery charging made easy
Protects electronics on house battery circuit from engine start up spikes
Fully automatic
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VOLTAGE DROP CHART
Total Cable
Length (m)
Total Cable
Length (ft)
Amps
Voltage
Drop (%)
mm²
AWG
3
3
50
00
2.3%
3%
4 mm
6 mm
0
2
2
6
6
50
00
3%
3.5%
6 mm
0 mm
0
7
3
3
9
9
50
00
2.7%
3.4%
0 mm
6 mm
7
5
4
4
2
2
50
00
3.6%
2.6%
0 mm
25 mm
7
3
5
5
5
5
50
00
2.8%
3.3%
6 mm
25 mm
5
3
6
6
8
8
50
00
3.4%
3.9%
6 mm
25 mm
5
3
7
7
2
2
50
00
3.9%
4.6%
6 mm
25 mm
5
3
8
8
24
24
50
00
2.6%
25 mm
3
SPECIFICATIONS
Continuous 25 Amps
Intermittent 40 Amps
Ignition Protected UL07
System size
2 V DC
24 V DC
Engages
3.7 V DC 27.4 V DC
Disengages
2.8 V DC 25.6 V DC
24 V DC system is 70-25A-24V
Z168
BEP’s unique VSR
Modern charging systems must be able to safely charge two or
more different types of batteries from one engine.
Now, thanks to BEP’s unique VSR (Voltage Sensitive Relay) boat
owners can enjoy the benefits of fully charged engine starting
batteries and deep cycle house batteries with one easy-to-install
charging system.
70-25A (SINGLE SENSE) VSR OPERATION
The Voltage Sensitive Relay (VSR) allows two batteries to be
charged at the same time. When the engine is started and the start
battery reaches 3.7 volts, the VSR engages, allowing two battery
banks (start and house) to be charged simultaneously. When the
voltage drops below 2.8 volts (eg the engine is stopped), the VSR
disengages, separating the batteries.
This system eliminates the possibility of draining the wrong battery
and protects sensitive electronic equipment powered from the
house battery from harmful engine start up spikes.
70-25A-DS (DUAL SENSE) VSR OPERATION
Same as the 70-25A with the added feature of dual sensing.
This allows the unit to sense the voltage of both batteries that it is
connected between. If either battery is receiving a charge the VSR
will activate paralleling the two battery banks.
The 70-25A-DS is designed for situations where a battery charger
or second charging source is used into the house battery.
Q: To which side of the battery switch should the VSR be wired?
A: It is vital to follow the wiring installation diagram which shows
correct connection to the master switch. BEP only recommends
the supplied option. Other options can lead to accelerated battery
discharge as the sense circuit draws 0.0 Amps continuously. The
output wire of the VSR should always be connected to the battery
side of the House battery switch to ensure true isolation of house
circuits if the VSR is engaged.
Q: Why does the LED stay on after engine is turned off?
A: System voltage has not dropped below 2.8 V DC due to battery
charging. VSR will disengage once residual battery voltage drops
below 2.8 V DC.
Q: How do I ensure that the correct size of battery is matched
to my VSR?
A: See the battery sizing chart on next page.
Q: Why does my VSR ‘chatter’?
A: Because the charging system is too small for the batteries and
this is not allowing the VSR to work properly. Instead, once the
starting battery has reached the right voltage and the house battery
is connected the systems voltage is ‘caving down’ below 2.7 volts
and the relay is automatically disconnecting. The voltage then rises,
the relay re-engages; then the voltage drops the relay disengages
and the ‘chattering’ sound is heard as the relay quickly switches in
and out. Refer to battery sizing chart on next page.
More information can be found on our Website www.bepmarine.com.
Important information
Frequently asked questions
IMPORTANT
It is the installer’s sole responsibility to install and use this product in a manner that will not cause accidents, personal injury or property damage.
Please follow the installation instructions supplied. If installation is not correct, the unit may not perform at its designed potential. If in doubt,
consult your local BEP Marine dealer. BEP Marine Limited disclaims all liability for any use of this product that may cause accidents, damage or
be a violation of any laws.
Copyright © 2007 BEP Marine Limited. All rights reserved.
