Blue Sea Systems
Blue Sea ML-RBS 7700 wiring diagram
12 V magnetic-latching remote battery switch with manual override and LOCK OFF. Rated 500 A continuous with two 4/0 AWG cables per stud and 300 A live switching at 12 V. Requires a separately fused supply and momentary open/close controls.
Wiring diagram
How the ML-RBS is wired.
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Cable sizing for this example
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Installation notes
Before you install.
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Verified against the manufacturer's documentation (rev. 990180170 Rev.006), checked 2026-10-01. Manufacturer documentation →
Which remote switch is shown?
Blue Sea 7700 is the 12 V ML-Series remote battery switch with manual control. It uses a magnetic latch: the main switch draws no continuous coil current while held open or closed. The 7700/7702/7701/7703 manual, PDF pages 1–2, distinguishes the 12 V 7700 from the 24 V 7702 and the solenoid versions without the manual knob.
The remote coil's voltage rating must match the control supply. The wider published contact-voltage range does not turn a 12 V control coil into a 24 V coil.
Where do power and control wires connect?
A and B are interchangeable high-current studs: battery to either stud, switched circuit to the other. They are the only terminals shown on this catalog drawing. Battery current does not pass through the remote rocker switch.
The small harness is essential. Red is the always-available positive supply, through the manual's minimum 10 A protection; black is DC negative. Brown receives a momentary positive command to close and orange a momentary positive command to open. Yellow operates the indicator connection. The diagram supplies the momentary switch common and LED positive through minimum 2 A protection, using a battery-side source so the switch can reopen or close regardless of main-contact state. Follow page 2 when matching fuse characteristics to the actual control wiring.
What can it carry and interrupt?
Page 1 qualifies 500 A continuous with two 4/0 AWG cables per stud. Its table reduces continuous capacity to 300 A with one 4/0 cable and 225 A with 2/0. The separate 12 V live-switching rating is 300 A, not 500 A.
The 3/8-inch–16 main studs use a maximum torque of 140 in-lb (15.8 N·m). Install near the bank in a dry, protected location, away from vented lead-acid battery gases. Provide separate circuit protection for inverter, windlass, thruster and other applicable feeders; the switch is not a fuse.
What must be checked before relying on remote operation?
Use the specified momentary control. Holding a command for five seconds invokes coil protection and can prevent a response for about ten seconds. Verify both remote directions, indicator operation and manual operation after installation.
For service, use the physical LOCK OFF position and its securing provision. A latching contact retains its state when control power disappears; it is not automatically a fail-open BMS disconnect. The drawing omits the entire harness, command switch and control protection, so those remain part of the installation design.
Fit check
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Technical reference
Specifications and terminal map.
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Catalog specification
12 V magnetic-latching remote battery switch with manual override and LOCK OFF. Rated 500 A continuous with two 4/0 AWG cables per stud and 300 A live switching at 12 V. Requires a separately fused supply and momentary open/close controls.
Connection limits are listed in the terminal map. Use the manufacturer's documentation for the full specifications.
Terminal map
Catalog connection points, current direction and planning limits. Check the manufacturer's pinout and connector ratings before installation.
A
neutral · input
B
neutral · output
Sources and sizing method
Equipment specifications. Model details, ratings and terminal roles come from the catalog. Check your unit’s label and current manufacturer documentation for its exact revision.
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