Product Catalogue

710-125A - Voltage Sensitive Relay

1. Q. Why does LED stay on when engine is switched off?
A. When the engine is switched off there is normally a residual voltage above the 12.8 volt drop out voltage. The voltage will eventually drop below 12.8 volts and the VSR will disengage. If the engine is started while the VSR is engaged it will immediately disengage as the load from the starter motor drops the voltage.

2. Q. Why can I start my engine when the start battery switch is switched off?
A. System is being energized because VSR is still engaged. VSR wires need to be changed to the battery side of the battery switch.

3. Q. Why is my VSR chattering?
A. This is normally due to the charging system being too small for the size of the second battery and loads. We recommend reducing the size of the second battery and review loads.

4. Q. What is the difference between a single or dual sense VSR?
A. The single sense VSR will only sense off one battery, normally your start battery, where it picks up the charge voltage rise from the engine alternator.
The dual sense VSR will sense both batteries. This means it will also engage if a battery charger is connected to the second battery and the voltage is above 13.7 volts.

5. Q. How close to the batteries should I mount the VSR?
A. We recommend the VSR be mounted as close as possible to the batteries or battery switches making the cables as short as possible.

6. Q. Should my VSR get warm when operating?
A. The VSR will get warm however can still be touched by hand.

7. Q. What does the VSR draw?
A. In disengaged mode the current is 10 mA

8. Q. When should my VSR engage?
A. When the sensed battery has reached 13.7 volts.

9. Q. When should my VSR disengage?
A. When the engine or charging source is switched off and the residual voltage drops below 12.8 volts.

10. Q. How does my battery charger fit into the wiring of the VSR?
A. If using a Dual sense VSR you can connect your battery charger to either bank of batteries. When the charger brings the battery above 13.7 volts the VSR will engage and parallel the second bank. This will happen if you are connected to the start or the house battery.
A. If using a single sense VSR as used on BEP Clusters you can connect the charger to the House battery and this will charge the house bank only. If you connect to the start battery it will charge the start battery first then engage the VSR and charge the house battery.
A. The battery charger can be connected at the battery pos and neg connections.

11. Q. How does my VSR relate to my regulator?
A.The VSR is not connected to the regulator. The regulator controls the alternator. The VSR parallels the second battery when the voltage on the start battery reaches 13.7 volts and disengages the second battery when the engine is stopped and the voltage drops below 12.8 volts. The VSR is a means of charge distribution not charge control.

12. Q. Do I do anything with the engine alternator or regulator when installing a VSR?
A. No. The VSR is linked to the batteries only.

13. Q. What size wire do I run from battery switches to batteries.
A.This will be different for each installation and is dependent on the size of the battery bank, alternator and starter motor. We suggest you consult your local marine electrician for advice on your installation.

14. Q. Why am I not getting any charge from my VSR.
A. There could be a number of reasons please check the following.

  • Is alternator charging when engine is running.
  • Is negative wire for VSR connected.
  • Is LED on front of VSR showing when engine is charging. If yes and second battery is not being charged there could be a problem inside VSR, please return to your local agent for testing.
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