12V 140A Voltage Sensitive Relay Kit – Dual Battery Isolator IP65 – Model 4 m

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The 12V 140A Voltage Sensitive Relay Kit – model 4 m is designed to equip a vehicle or onboard installation with a 12V auxiliary battery placed at a moderate distance from the main battery. This version is ideal when wiring needs to pass through a trunk, cell, technical compartment, or part of the vehicle.

The relay automatically couples the two batteries when the charging voltage is sufficient, then separates them when the voltage drops. This allows the auxiliary battery to be charged while keeping the starting battery available when the engine is off.

Key features

• Main cable 4 m: convenient for batteries separated by an intermediate cable passage.
• Automatic charge management: no need for manual action daily.
• Engine battery protection: automatic separation when the voltage drops.
• 12V 140A Relay: suitable for onboard auxiliary installations.
• IP65 Case: protection against dust, moisture, and water splashes.
• Complete kit: cables, terminals, fuse holder, lugs, and accessories included.
• 2-year warranty.

This 12V coupling-separating kit allows for creating a reliable dual battery installation to power auxiliary equipment without directly using the starting battery when stopped. It is suitable for converted vehicles, utility vehicles, 4x4s, boats, and leisure installations requiring a service battery.

The 4 m version offers more flexibility than the short model. It is suitable for configurations where the auxiliary battery is not right next to the main battery but remains within a reasonable distance: rear of the cabin, technical trunk, storage compartment, hold, light cell, or fitted area.

The relay operates according to the detected voltage. When the circuit reaches about 13.3V, the batteries are connected to allow charging. When the voltage drops to around 12.8V, the relay isolates the batteries to limit the discharge of the main battery.

For which installations to choose the 4 m version?

This model is recommended when the 2 m version would be too short, but it is not necessary to switch to a long cable length. It is particularly suitable for:

• converted van with auxiliary battery in the trunk or under the bench seat;
• utility vehicle with service battery in the rear area;
• 4x4 or pickup with remote auxiliary equipment;
• motorhome with nearby technical compartment;
• boat or small 12V marine application;
• ATV, UTV, trailer or leisure vehicle equipped with 12V.

Automatic operation of the relay

• Activation when the voltage reaches about 13.3V.
• Coupling of the two batteries to allow charging.
• Deactivation when the voltage drops to about 12.8V.
• Separation of the main battery and the auxiliary battery.
• Disengagement delay of about 5 to 10 seconds.
• Operation without mandatory ignition control wire, the relay is based on the detected voltage.

Technical specifications

• Model: JDQTJ-4M
• Version: 4 m model
• Product type: voltage-sensitive relay / dual battery isolator
• Nominal voltage: 12V DC
• Continuous current: 140A
• Intermittent current: 160A
• Activation voltage: 13.3V
• Cut-off voltage: 12.8V
• Protection rating: IP65
• Housing material: nylon plastic
• Operating consumption: 280 mA
• Standby consumption: 8 mA
• Power studs: stainless steel M6
• Activation delay time: 5 seconds
• Disengagement delay: approximately 5 to 10 seconds
• Operating temperature: -30°C to +105°C
• Relay dimensions: 6.76 x 5.36 x 6.76 cm
• Net kit weight: approximately 1.88 kg
• Warranty: 2 years

Box contents

• 1 separate 12V charge relay
• 1 red battery cable 110A of 4 m
• 1 black ground cable 110A of 1 m
• 1 positive marine battery terminal
• 1 negative marine battery terminal
• 2 fuse holders
• 3 lug connectors
• 3 insulated blue ring terminals
• 15 cable ties
• 2 red cables 110A of 250 mm
• 2 heat shrink tubes
• 1 drill bit
• 1 black split conduit
• 1 set of screws

Advantages of the 4 m version

The 4 m model is a good compromise for setups where the batteries are not side by side. It allows for a cleaner cable routing in a converted vehicle, while avoiding excessive length if the installation remains relatively compact.

This version is particularly useful for onboard 12V equipment such as:

• auxiliary lighting;
• cooler or small 12V refrigerator;
• water pump;
• accessory socket;
• small onboard equipment;
• leisure or camping power supply.

Installation tips

Before installation, check the 4 m cable route between the two batteries. The cable must not be taut, pinched, exposed to excessive heat, or in direct contact with a metal edge.

For a reliable installation:

• attach the relay to a stable and accessible surface;
• observe the polarity of each battery;
• install the provided protections according to the diagram;
• secure the cables with the ties;
• protect the passages exposed to friction;
• check the terminal tightness after installation;
• have the installation validated by a professional if in doubt.

This kit is intended for 12V DC only installation. It is not suitable for 24V or 48V systems.

This is an automatic coupling-separating relay, not a DC/DC charger. For certain lithium batteries or installations requiring precisely regulated charging, it may be necessary to use a DC/DC charger suitable for the auxiliary battery.

If your batteries are very close, the 2 m model may suffice. If the auxiliary battery is installed further in the vehicle, the 5 m or 6 m versions may be more suitable.

2-year warranty

VEV / 15862