175A Continuous Rating Battery Isolator Switch DC 12V-36V ON-OFF Two-Position Rotary Battery Disconnect Switch for Boat RV

The MT040 is a two-position master switch for DC wiring that needs a reliable cut-off point. Rotate once to connect, rotate back to isolate — there is no intermediate setting, so nobody has to guess what the dial is doing when the boat is being put away or a technician is working on the loom.

Its contact assembly is rated 175 amps continuous and accepts a supply anywhere between 12 and 36 volts, which lets the same part number serve a 12V tender, a 24V workboat and a 36V electric-drive installation without splitting the stock list.

The rotating knob sits over a moulded housing with a flat mounting flange, so it can be fastened to a dash panel, console face or battery compartment wall. Studs are sized for standard ring lugs, keeping the joint surfaces large enough that a long charging session will not cook the terminals.

• Powerboats and sailboats — master isolation for engine, navigation and domestic circuits.
• Motorhomes and camper conversions — leisure battery cut-off for lay-up periods and travel.
• 4x4, pickup and utility vehicles — winch, light bar and accessory fuse-board feeds.
• Electric-drive and 36V equipment — isolation on higher-voltage DC packs inside the rated window.
• Workshop and plant — shared machinery and trailers needing a lockable-off style disconnect.

• Positive ON / OFF detents — the knob clicks into each end position, so a half-turned switch is impossible.
• Copper internal conductors — low resistance path with less heat build-up at the studs than plated steel.
• Moulded housing with mounting flange — rigid base that stays flat when the fixing screws are tightened.
• Large stud diameter — heavy lugs land properly without reducing cable cross-section.
• Wide 12V–36V window — one SKU covers several system voltages, simplifying spares holding.
• Legible dial legend — ON and OFF readable at arm's length and identifiable by feel.

1. Shut down all loads, remove the battery negative first, and confirm the circuit reads dead on a meter.
2. Choose a flat surface with clearance around the knob and enough depth behind it for cable sweep.
3. Hold the switch in place, mark the flange holes, drill, then fix it down evenly.
4. Terminate the supply cable on one stud and the load or fuse-board feed on the other.
5. Use crimped ring lugs on both ends and tighten the nuts fully — a slack joint is the usual cause of heat.
6. Exercise the knob once with loads disconnected, then reconnect and check stud temperature under load.

Set the switch to OFF whenever the vessel or vehicle is stored, transported or handed to service staff. Wipe salt film off the knob and housing after coastal trips, and check nut torque at the start of each season. Any cable showing green corrosion or discoloured insulation should be replaced rather than retightened — the isolator cannot outperform its terminations.

• 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.