12V-48V DC Marine Battery Isolator Switch 250A Continuous 1000A Cranking Battery Disconnect Switch

Cutting power on a boat or a camper should be one unmistakable action, not a guess. The MT066 gives you a two-position rotary dial with a hard detent at each end, so anyone on board can tell at a glance whether the bank is live or dead. Behind that dial sits a solid copper contact bridge rated 250A continuous and 1000A cranking, wrapped in an ABS shell that tolerates salt spray, fuel mist and strong sunlight.

The real advantage is the voltage window. This one part number runs on a 12V tender, a 24V truck, a 36V golf car or a 48V electric outboard — so a dealer or a fleet workshop stocks a single switch instead of four. Fewer SKUs on the shelf, fewer wrong-part returns.

• Single-battery and dual-battery boat layouts, including trolling motor circuits
• RV, motorhome and camper house banks where a master kill switch is required
• Winch, windlass and thruster feeds that need a manual hard break
• Workshop and agricultural equipment stored for long periods
• Solar and off-grid installations with 48V nominal strings

A frequent mistake is quoting the cranking figure as if it were a working load. Contacts that are asked to carry 1000A continuously will discolour and eventually weld. Size the cable against 250A, treat 1000A as a short burst, and the switch will outlast the installation around it.

The housing is moulded ABS rather than a soft thermoplastic, so terminals stay aligned when heavy lugs are torqued down and the body does not creep in hot engine rooms. Inside, the current path is copper — lower resistance than plated steel, less heat at the studs, and a cleaner contact face after years of cycling.

• Two-position rotary — ON and OFF only, with a positive stop so vibration cannot drift the dial
• Large stud terminals — accept ring lugs sized for 250A cable without shaving the conductor
• Detented dial face — ON/OFF marking readable at arm's length and identifiable by touch
• Rear mounting base — panel or bracket fixing on a flat rigid surface
• Sealed body joint — keeps spray and dust away from the contact set

1. Turn the dial to OFF and disconnect the negative lead first. Confirm dead at both studs before touching anything else.
2. Choose cable cross-section against 250A continuous, not the 1000A cranking figure.
3. Fix the switch to a flat, rigid panel. A flexing surface will loosen stud nuts over time.
4. Bank positive to one stud, distribution or starter feed to the other. Closed ring lugs only.
5. Crimp with the correct die, then torque both nuts fully. Never rely on hand-tight.
6. Cycle the dial once with no load, reconnect the bank, then check stud temperature after the first loaded run.

• Model: MT066, ON-OFF two-position rotary
• Material: ABS housing with copper current path
• Ratings: 250A continuous, 1000A cranking, DC 12V–48V
• Minimum order: 5 pieces; price quoted against quantity and packing
• Lead time: 30 days for standard production
• Payment: T/T or Western Union, 30% deposit with balance before shipment
• Packing: Carton

Need a sample or a quotation for a mixed container? Send your cable size and system voltage and we will confirm the correct MT066 configuration.