125A Voltage Sensitive Relay | 12V Dual Battery Isolator

Automatic Dual Battery Charging

Forget manual battery switches.

A Voltage Sensitive Relay automatically monitors your vehicle's battery voltage and intelligently connects your auxiliary battery once charging voltage is detected.

When the engine is turned off and voltage drops, the relay isolates the batteries, ensuring your starter battery remains protected for reliable engine starting.

Protect Your Starter Battery

Running fridges, lights, Starlink systems or camping accessories from your auxiliary battery shouldn't leave you with a flat starter battery.

This VSR helps:

✔ Automatically charge both batteries

✔ Protect the starting battery

✔ Eliminate manual battery switching

✔ Reduce wiring complexity

✔ Improve overall system reliability

Heavy Duty Performance

Designed for demanding applications, this Voltage Sensitive Relay features:

✔ 125A continuous current rating

✔ 140A intermittent rating

✔ Automatic voltage sensing

✔ LED operating indicator

✔ IP67 weather-resistant housing

✔ Glass fibre reinforced nylon construction

✔ Surface or panel mounting

✔ M6 terminals

✔ Maintenance-free operation

What does a Voltage Sensitive Relay do?

A VSR automatically connects your auxiliary battery for charging once the vehicle's charging system reaches the preset voltage and disconnects it when the engine is switched off, helping protect your starter battery.

Is this suitable for caravans and 4WDs?

Yes. It's ideal for caravans, camper trailers, 4WDs, motorhomes, boats and other 12V dual battery systems.

What is the current rating?

The relay is rated for 125A continuous and 140A intermittent current.

Does it require manual switching?

No. The relay automatically combines and isolates the batteries based on system voltage, making operation completely automatic.

Is it weather resistant?

Yes. The housing is rated IP67, making it suitable for demanding automotive and marine environments when installed correctly.