2500A Peak Cranking Marine Battery Isolator Switch with 250A Continuous Rating and ON-OFF Two-Position Rotary Battery Disconnect Switch

Engine start is a different job from running a DC board. For a fraction of a second the starter asks for current many times the normal working figure, and a switch with a thin contact set will pit, weld or heat up. The MT032 is specified for both halves of that duty: 250 amps continuous, and a 2500 amp peak held for up to five seconds, on 12 or 24 volt systems.

It is a two-position rotary unit: ON closes the circuit, OFF isolates it, each with a hard mechanical stop. There is no selector position to get wrong, which matters in an engine compartment where the operator is often working by touch in poor light.

Housing, studs and contact path are sized for engine-room conditions rather than a tidy dashboard. Cable gauge and lug quality still decide how the switch performs, so the tables below are worth checking before the unit goes in.

The peak figure is not a continuous rating and must never be treated as one. It exists so that a diesel or large petrol engine can be cranked through the switch without damage, inside a five-second window that matches normal starting behaviour.

• Vibration — detented ON and OFF positions mean the dial cannot creep out of contact.
• Heat — copper current path limits resistance, so the studs stay cooler during long charging runs.
• Space — a flat mounting base fits bulkheads and battery box walls without an adapter.
• Heavy cable — large studs take proper ring lugs without cutting cable cross-section.
• Service access — OFF gives a full break before anyone touches the starter circuit.

1. Turn the dial to OFF and disconnect the battery negative lead first.
2. Confirm the circuit is dead at both switch studs with a meter.
3. Fasten the body to a flat surface that will not flex under cable weight.
4. Land battery positive on one stud and the starter or distribution feed on the other.
5. Fit closed ring lugs, crimped with the correct die, then torque both nuts fully.
6. Cycle the dial once without load, reconnect the battery, crank the engine, then feel the studs for heat.

Shut the engine and any heavy load down before turning the switch. Never open a 2500A-rated circuit under load; the arc will damage the contacts. Keep the dial free of oil and salt, check nut torque at every service, and replace cable with heat damage rather than retightening it.

• Minimum order — 5 pcs.
• Price — negotiable, quoted against quantity and packing requirements.
• Capacity — 50,000 pcs per month.
• Lead time — 30 days for standard production.
• Payment — T/T or Western Union; 30% deposit with the balance before shipment.
• Packing — neutral white box inside a brown carton; branded packing available with written trademark authorisation.