• 4x4 split charge relay 140 amp
  • Split charge relay kit 12V 140A
  • Voltage sense split charge relay for camper
  • Dual battery split charge kit 140A
  • Intelligent split charge relay van conversion
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AutoSmart Parts

Split Charge Relay Kit 12V 140A, Voltage Sense Dual Battery for Camper Van and 4x4

Running a fridge, lights or pump from your leisure battery without draining the starter? This 140A split charge relay senses the engine running and charges both batteries automatically.

$149.99 AUD
$170.00 AUD $149.99 AUD
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check 140A intelligent voltage sense for canbus vehicles
check No ignition feed wire needed, install in minutes
check Isolates leisure battery so starter battery is never drained
check Complete kit: relay, cables, fuses, terminals, fittings

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Specifications

Type: Intelligent voltage sense split charge relay
Voltage: 12V
Current rating: 140A
Cable: 10mm² red PVC 70A power cable plus 1m black PVC 70A earth cable
Fuses: 4 × 60A MTA MIDI fuses (2 spares included)
Fuse holders: 2 × MTA MIDI fuse holders
Terminals: 1 pair 8mm post type battery terminals
Variants: Cable lengths 3m, 5m, 7m, or relay only; with or without LED indicator

Compatible With

Vehicles: Camper vans, motor homes, 4x4s, day vans, mobile workshops, cars, boats
Voltage: 12V only
Best for: Modern vehicles with canbus controlled wiring (no ignition feed needed)
Batteries: Connects starter battery to leisure / auxiliary battery (sold separately)

What’s Included / Care Instructions

What's included:
• 12V 140A intelligent voltage sense split charge relay
• 70A power cable (length per variant: 3m, 5m, 7m, or relay only)
• 1m 70A earth cable
• 2 × MTA MIDI fuse holders
• 4 × 60A MTA MIDI fuses (2 spares)
• 1 pair 8mm post type battery terminals
• Heat shrink for connections
• 10 × cable ties + 10 × adhesive base fixings
• 15 × fixing screws
• Fitting instructions with wiring diagram
• LED indicator (LED variants only)

Care:
• Mount relay in a sheltered location
• Route cables through grommets to prevent chafing
• Check fuse first if leisure battery stops charging

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Install Guide

1. Disconnect Batteries

Disconnect both starter and leisure battery negative terminals before any wiring work.

2. Mount Relay and Run Cables

Mount the relay roughly midway between the two batteries. Route the red 70A cables from each battery (via the inline fuses) to the relay terminals. Connect the earth cable to chassis ground.

3. Reconnect and Test

Reconnect both batteries. Start the engine and check the relay engages (LED variant lights up). Stop engine and confirm relay drops out, isolating the leisure battery.

Common Questions Before You Buy

What does intelligent voltage sense mean?
The relay detects rising voltage from your alternator (above about 13.3V) when the engine runs, then connects both batteries so they charge together. When voltage drops (engine off), the relay disconnects, isolating the leisure battery.
Will it work on a modern canbus vehicle?
Yes, this is specifically designed for modern canbus controlled wiring. No ignition feed wire needed, so no risk of error codes or fuse problems.
Which cable length should I choose?
3m for compact installs (engine bay to underseat battery). 5m for larger vans or 4x4s with battery in the boot. 7m for camper vans with the leisure battery far from the alternator.
What's the LED indicator for?
The LED lights up when the relay is engaged (both batteries connected and charging). Handy for monitoring the system, but optional. The no LED variants work the same way without the visual indicator.
Is the leisure battery included?
No, this is the relay kit only. Pair it with any deep cycle leisure battery (sold separately). Lead acid AGM is most common, lithium LiFePO4 also works well.