DC 48V Marine Battery Isolator Switch with 2500A Cranking and ON-OFF Two-Position Rotary Battery Disconnect Switch

Large DC banks punish weak hardware. The MT029 is built for the top end of the marine and vehicle market: 48-volt systems, 300A to 500A working current, and a 2500A cranking window measured over five seconds. It is the switch you fit when the load is an electric drive, a large lithium bank, a thruster set, or a heavy diesel that draws hard for a moment before it fires.

Two positions, ON and OFF, with a hard stop at each end. There is no selector linkage to wear and nothing to misread. The contact assembly is sized for the full working and cranking figures rather than being a light-duty body with a generous label.

Studs are large, the mounting base is rigid, and the dial is designed to be turned by hand under load-free conditions. Cable gauge, lug quality, and nut torque matter more at this current level than at any other point in the DC system, so the installation notes below are worth following closely.

• 48V electric drive boats — main pack isolation between battery bank and controller.
• Large lithium installations — master break on high-capacity house banks.
• Thruster and windlass feeds — heavy consumers that need a dedicated isolate point.
• Heavy diesel start circuits — cranking loads inside the five-second window.
• Commercial vehicles and plant — battery isolation on high-draw work equipment.

• Full-size contact set — dimensioned for the working and cranking ratings shown above.
• Copper current path — low resistance and controlled stud temperature under sustained load.
• Reinforced mounting base — resists distortion when large studs are torqued down.
• Heavy terminal studs — accept large ring lugs without reducing cable cross-section.
• Two-position rotary action — positive stops at ON and OFF, no intermediate state.
• Clear dial legend — state visible at a glance and identifiable by touch.

1. Isolate the bank, remove the negative lead first, and verify dead with a meter at the studs.
2. Select cable cross-section for the working current, not the cranking figure.
3. Mount on a flat rigid surface that can carry the weight of heavy cable without flexing.
4. Connect the bank positive to one stud and the load or controller feed to the other.
5. Use closed ring lugs only, crimped with the correct die, then torque both nuts fully.
6. Operate ON-OFF once without load, reconnect, and check stud temperature after the first working run.

• 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.