Blue Sea Systems ML Solenoid, 500A, Auto-Releasing

Overview

The Blue Sea Systems ML-Series Solenoid Switch is a 500A auto-releasing magnetic latching solenoid for remote high-current DC switching on boats. It is made for battery and DC distribution circuits where the switching point may be close to the batteries, while control is handled from a helm, electrical panel, or other remote location.

The range covers both 12V DC and 24V DC control systems. The 12V versions use a 10.1 to 16.5V DC control circuit, while the 24V versions use a 20.2 to 32.9V DC control circuit. Main cable connections are made through 3/8"-16 (M10) tin-plated copper studs, with a listed terminal torque of 140 in-lb (15.82 Nm).

The auto-releasing coil function works well where a sustained control signal is needed to act like a normally open relay, while keeping control-circuit draw very low at 8mA when off and 13mA when on. This makes the solenoid a strong fit for boats that need remote high-current control without adding unnecessary load to the control side of the system.

Key features

• 500A magnetic latching solenoid for high-current battery and DC distribution switching under load.
• Auto-releasing coil function for normally open relay behavior with SPST or SPDT control switching.
• Low control draw of 8mA when off and 13mA when on for vessels that keep remote switching circuits energized.
• Silver alloy contacts support live-load switching in demanding DC systems.
• 3/8"-16 (M10) tin-plated copper studs help maintain conductivity and resist corrosion at the main cable terminals.
• One-piece stainless flange nuts give the high-current cable connections a secure clamping point.
• 700A intermittent rating for 5 minutes and 300A live current switching rating at 12V DC.
• Terminal ring clearance of 1.18 in (29.97 mm) and stud length of 0.875 in (22.23 mm) help confirm cable-end fit before installation.
• Operating temperature range from -10 C to 60 C, with mechanical endurance rated at 100,000 cycles.
• LED output allows remote switch-state indication when paired with a compatible LED or Contura switch with integrated LED.

Variants

This ML-Series solenoid is offered in 12V DC and 24V DC configurations, with either tinned wire control leads or a Deutsch DTM / Amphenol ATM control circuit connection.

The auto-releasing coil function, #10 mounting, 3/8"-16 (M10) main terminal studs, 140 in-lb terminal torque, and included Remote Control Contura Switch are consistent across the listed configurations. The control voltage range and change-state current follow the selected nominal voltage.

• 7718: Tinned wire control circuit connection, 12V DC nominal voltage. This version fits 12V DC control wiring where wire leads are brought directly into the remote switch circuit.
• 7718100: Deutsch DTM / Amphenol ATM control circuit connection, 12V DC nominal voltage. This version keeps the 12V control range while using a plug-style control connection for harnessed installations.
• 7719: Tinned wire control circuit connection, 24V DC nominal voltage. This version matches 24V DC control systems while keeping the direct wire-lead connection format.
• 7719100: Deutsch DTM / Amphenol ATM control circuit connection, 24V DC nominal voltage. This version matches 24V DC control harnesses that use the DTM / ATM connector format.

Electrical and system integration

This is a remote high-current solenoid, not a battery combiner or automatic charging relay. It is used to open and close a DC circuit from a control switch, which is helpful when the main battery cables need to stay short and the operator control needs to be somewhere more accessible.

Cable sizing to meet the listed ratings is 2x (4/0), so the installation should allow enough space for large cable bends, ring terminals, and strain relief. The solenoid should be mounted on a solid surface near the battery or high-current bus, with the high-current cable path kept as short and tidy as the vessel layout allows.

Installation notes

The #10 mounting, label recesses, and remote switch-state LED output make the unit practical for battery compartments, DC distribution areas, and helm-controlled switching layouts. The selected variant should match both the vessel control voltage and the preferred control connection style before the main cables are terminated.

For service planning, the remote control function and switch-state indication can reduce the need to access the battery space during normal operation. On cruising boats, fishing boats, and larger 24V vessels, that matters when the electrical gear is tucked away in a locker, engine room, or dedicated electrical compartment.

What’s included

• Remote Control Contura Switch - ON-ON