32V DC 675A Cranking Marine Battery Isolator Switch with 300A Continuous Rating for Boat and RV

Read the MT083 label in order and it tells a story: 300A continuous, 450A for five minutes, 675A cranking. Each figure is exactly fifty percent above the one before, and each describes a different length of time rather than a bigger product. That ladder is the most useful thing about the switch, because it lets a fitter decide which number applies to the job in front of them.

The body is rated to 32V DC, which suits 24V systems with headroom for charging voltage, and the dial is a plain ON-OFF rotary with a positive stop at each end.

• Step one — 300A Every load that can run together, indefinitely. This is the only figure a cable or a fuse should be chosen from.
• Step two — 450A One and a half times continuous, limited to five minutes. Thruster bursts, windlass pulls and inverter peaks live here.
• Step three — 675A Another fifty percent, measured in seconds rather than minutes. A starter motor on a cold morning is the only thing that should ever draw it.

• Mid-size cruiser or RIB — Single 24V bank feeding electronics, pumps, a fridge and a windlass from one master break.
• Motorhome and camper — A hard dead point ahead of the distribution panel for storage, transport and service work.
• Work truck and plant — Stops battery drain on equipment that stands for weeks between jobs.
• Off-grid cabinet — Manual isolation for a 24V string before maintenance, without pulling a fuse.

• Size the cable against 300A Apply margin for length, ambient temperature and bundling. The 450A and 675A figures describe events, not steady state.
• Fuse at the battery end The fuse protects the cable between battery and switch. The switch only gives you a way to break the circuit.
• Keep the run short Voltage drop on a 24V system costs more than on 12V; a shorter cable saves both heat and money.

1. Dial to OFF, negative lead off first — Prove zero volts at both studs.
2. Fix the body to rigid material — Rear base on a flat panel; a flexing surface loosens the stud nuts.
3. Land closed ring lugs — One stud to the bank positive, the other to the starter or distribution feed.
4. Torque both nuts — Then re-check after the first week in service.
5. Load test and feel the studs — Warm is normal. Too hot to hold means the joint needs attention.

Tell us the continuous load, cable size and mounting point and we will confirm the MT083 configuration, packing and freight. No minimum quantity required.

• Marine Battery Isolator Switch
• Marine Isolating Switch
• Boat Isolator Switch