KICKASS 12 Volt 140 Amp Dual Sensing Voltage Sensitive Relay

RRP $99.00
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Product Description

Featuring a massive 140 Amp current rating the KICKASS® advanced Voltage Sensitive Relay (VSR) with override is a specially designed battery isolator which has the intelligent ability to sense both start and auxiliary battery voltages. This allows it to engage or isolate depending on each battery's voltage level.  A huge advantage of this dual sensing VSR is that when the auxiliary battery is being charged by solar or an AC battery charger and it is above 13.2V the VSR will engage which will enable the starting battery to also be charged.

In normal operation this VSR will engage when the engine is running and the start battery reaches 13.2V. This will connect the start and auxiliary batteries enabling your alternator to charge them simultaneously. When the engine is not running there is no charge from the alternator to the battery and the voltage will drop. Once the voltage reaches 12.8V the VSR will disconnect from the auxiliary battery. This means that the auxiliary battery can NOT drain your start battery.

A smart manual override switch is also incorporated and can be used to manually engage and connect the start and auxiliary batteries. This feature can be used when the start battery is low on charge and the auxiliary battery is still charged. Note: When the manual overide feature is used the auxilary battery takes time to charge the start battery it should not be used for instant starting. 

A remote switch can also be wired up to the unit to use the same feature.

The KICKASS® premium VSR also features a tough case which is hermetically sealed against weather and corrosion making it suitable for 4X4, marine, truck and industrial applications. The unit can be easily mounted to the firewall under the bonnet or almost anywhere else as it has easy surface mounting with convenient cable entry and exit points.

Key Features:

  • Charge you auxiliary battery without the risk of discharging your start battery
  • Protects electronics on auxiliary battery circuit from engine start up spikes
  • Fully automatic operation
  • Override switch (engages relay regardless of sense voltage)
  • Indication light wire (activates when VSR engaged)
  • Override wire (activated by + feed for optional remote operation)
  • Dual sensing - senses voltages of both start and auxiliary batteries



Input Voltage 12 Volt DC
Continous Current 140 Amp
Maximum Current 160 Amp
Dual Sense Cut In Voltage (Connect Voltage) 13.2 Volt DC with 15 Second Delay
Dual Sense Cut Out Voltage (Disconnect Voltage) 12.8 Volt DC with 15 Second Delay
Dimensions 88 x 90 x 55mm

Please download the instruction manual for further specifications and wiring diagrams.

Installation Guide


1. Connect the (+) positive wire from the start battery to the terminal on the VSR marked "Positive + Sense Batt".
2. Connect the (+) positive wire from the auxiliary battery's positive terminal to the terminal on the VSE marked "Second Batt Positive +".
3. Connect the thin black earth wire to either the vehicle chassis or the start battery's (-) negative terminal
4. Place the cover back onto the VSR then fix the VSR into place.

Optional Wiring

Override Wire - (Blue)
The blue override wire is not generally used however in some cases the user may want to engage the VSR manually by a remote switch or ignition feed. When this wire is connected to a (+) feed it will engage the VSR. If not required, this wire can be ignored.

Indication Light Wire - (Yellow)
This wire is active (+) positive when the relay is engaged. It can be connected to an external 12V light or led (not supplied) to indicate remotely when the VSR is engaged. IMPORTANT: As this wire is active (+) positive when the VSR is engaged, ensure it is cut off or insulated to ensure it can not short to earth when not being used.

For further details please download the full instruction manual here.


Product Reviews

Kickass VSR monitor

16 January 2018
Good quality. Only used it for the first time today and the light came on after about 30 seconds and ran an Engel car fridge all day from the second battery . Hopefully I won’t ever have a flat starter battery again

Awesome !

4 October 2017
Have installed and tested the VSR , all as clearly set out in directions , 100 pc. good ! However the package had been damaged and one side of fastening flanges was broken . I did not open the package on delivery - my fault - glued the broken bits back together an all is well , as stated before , maybe a bit of fill in the box might have saved it ? Kind regards Aksel

Excellent VSR

17 July 2017
Very happy with the many features such as dual sensing and override switch. Installation is a breeze and looks good.

VSR battery isolator

8 April 2017
Excellent product, easy to connect & works really well


2 March 2017
Quality products, fast delivery. Excellent customer service, recommendable

140 amp VSR

2 November 2016
excellent product and service

Battery isolator

22 June 2016
This isolator is brilliant I love not worrying about both batteries charging as well as when I plug my solar panels in to charge my aux battery that when its charged the isolator then closes to charge my start battery , reverse to normal function

Dual battery system

18 June 2016
Fitted the Kickass 140 amp VSR, works perfectly and was a dream to fit.

Vsr 140

15 April 2016
Easy to fit works a treat.