Voltage Sensitive Split Charge Relay - 12V 140A

Price:  £36.34(£30.28 Exc. VAT)

Product code:  P00705


In stock  

In stock

  (24 Reviews)
Thinking of installation a split charge system? Why not check out our Made-To-Measure Split Charge Kits


12V, 140A rated voltage sensitive relay for split charging applications in camper vans, motorhomes, 4x4s and boats. Allows charge to flow into one battery (or bank of batteries) only when a charging voltage is detected at the other battery (dual sensing operation).

  • Dual sensing operation - charges from starter battery to leisure battery when alternator is running and charges from leisure battery to starter battery when mains charger is connected.
  • Relay connects when sensed voltage reaches 13.7V or higher
  • Relay disconnects when sensed voltage drops to 12.8V or lower
  • Maintains battery isolation when not charging, so starter cannot be drained by leisure use and vice-versa.
  • Ignition protection to UL1107
  • Fully automatic operation
  • E Mark approval
  • Virtually zero voltage drop
  • Protects sensitive electronic equipment from harmful engine start-up spikes
  • Well proven design with 1000s of units operating in the field
  • Terminal connections marked on inside of unit for easy installation

Note: The benefit of this type of relay is that it does not require a connection to the alternator or any modifications to the existing vehicle electrical system.  Simply connect the +ve terminals on each of your batteries to the terminals on the relay and the black relay wire to a common -ve point.

An LED indicates when the relay is ON (contacts closed). Fixing holes in the body allow the unit to be mounted to a bulkhead and body cut-outs offer various cable routing options.

Fully encapsulated electronics make this unit splashproof and particularly suitable for harsh environments (marine use, vehicle engine bays etc.)

Sold individually. 

IMPORTANT NOTE: These relays are not suitable for vehicles with 'smart' or 'intelligent' alternators. As a guide this applies to vehicles having engines that comply with Euro5 emissions standards and onward, often also incorporating regenerative braking (if in doubt please consult your vehicle manufacturer to confirm). If your vehicle has a smart alternator then you will need to use a battery-to-battery charger instead of a VSR.


  • Sensing mode: Dual (2-way split charging, starter to leisure and vice-versa)
  • Voltage rating (nominal): 12V DC
  • Current rating: 140A
  • 'Cut-in' voltage: 13.7V
  • 'Cut-out' voltage: 12.8V
  • Terminal size: 2 x M6 studs and nuts
  • Other connections: Ground wire to connect to common -ve
  • Ground wire: 1mm2 - 50cm long approx.
  • Fixing hole dia: 5mm
  • Overall dimensions: 67 (W) x 67 (H) x 50 (D) mm


For more information on our battery-battery chargers and VSRs check out our YouTube Video 

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Average Rating (24 Reviews):  
Write a Review and share your opinions!

Split charge relay
Monday, 20 November 2017  |  Martyn

Easy to install. The holes for the wire entries could have done with being larger for my installation

Excellent, needs good earth!
Monday, 13 November 2017  |  Christopher

I fitted this and thought I'd done a neat and perfect job but something was wrong and the relay kept clicking on and off whenever I had a load on the leisure battery. Checking everything still didn't help until I discovered that the leisure battery earth was just a little insecure and wasn't giving me a good connection. Problem sorted. This is a very simple and efficient method of charging the leisure battery and I would heartily recommend it.

Friday, 21 July 2017  |  Mike

seems to have cured my battery charging problem

Voltage sensing split charge relay
Wednesday, 28 June 2017  |  Giles

After reading through the free useful info on the website I bought a VSR. Three connections to make and it's done. Definitely the easiest way to sort out charging of a second battery.

As described- and well made
Tuesday, 6 June 2017  |  Nick

Comes with diagram showing wiring options.

very pleased
Sunday, 4 June 2017  |  Jeff

the product is everything 12 volt planet said it was. i am very pleased with the delivery time and performance of the product. i will definetly order more from 12 volt planet as and when i need them.

Split charger relay
Friday, 31 March 2017  |  Michael

As they say, it does what it says

Thursday, 23 February 2017  |  Tom

works well charged all the batterries fitted in my motorhome via the solar panels!

Tuesday, 22 November 2016  |  Emil

The product is accurate to what I expected.

Split Relay
Tuesday, 9 August 2016  |  David

These are the units we fit to the window cleaning system which all the window cleaners are using. They are on and off all day 5 days a week. Not had one fail yet.
Customer service was 1st class when I had to contact them.

Read all 24 customer reviews...