Overview

The Blue Sea Systems 7601 is a compact m-Series automatic charging relay for 12V and 24V DC systems that manages charging between two battery banks with a 65A continuous rating and a 115A intermittent rating for 5 minutes.

It combines batteries while a charge source is present and separates them when charging stops, so a start battery and a house bank can charge from one alternator without staying tied together at rest. This model is dual sensing, which means it can react to charging on either battery bank, and it includes Start Isolation to keep house loads off the engine circuit during cranking.

For fit and wiring checks, the relay uses 1/4 in.-20 studs, accepts cable up to 1/0 AWG, and calls for 6 AWG cable to meet its current rating. The housing is rated IP67 for temporary immersion, and the unit is ignition protected for use on gasoline-powered boats when installed correctly.

Key features

• Handles charging current from alternators up to 65A on many outboard and smaller inboard charging systems
• Works with both 12V and 24V DC battery setups
• Dual-sensing operation monitors charging on either battery bank
• Start Isolation input separates the house side during engine cranking to reduce voltage drop and spikes at sensitive electronics
• IP67-rated housing and ignition protection suit the wet, vibration-heavy conditions found on board
• Compact body can be surface mounted, rear mounted, or panel mounted where space is limited
• LED status indicator and snap-on insulating cover make it easier to check operation and protect terminal connections
• 1/4 in.-20 studs with support for cable up to 1/0 AWG

Installation and setup

This relay fits boats with separate start and house batteries that need automatic charging management without manual switching every time the engine runs. It makes sense on single-engine outboards, skiffs, center consoles, and similar two-bank layouts where the alternator output stays within the 65A rating.

It is not intended to carry engine starting current. If the system may need emergency battery paralleling for starting, that function should be handled by a battery switch or another device built for that purpose. For longer service life, mount the relay in a dry, protected location and avoid placing it directly above battery banks.

The minimum setup uses one positive connection from each battery bank and a ground lead. The ground connection is fused at 1A, and the optional Start Isolation lead uses a fused 1A to 10A connection to the cranking circuit.

Compatibility and fit

This is a good match for boaters who want both battery banks to charge automatically from a single charging source while keeping the start battery isolated when the engine is off. It also suits installations where electronics on the house side benefit from temporary isolation during cranking.

Before ordering, check alternator output, available mounting space, cable size, and whether the boat uses a two-bank system. Installations with larger alternators, higher charging loads, or battery banks that are routinely paralleled for starting may need a higher-capacity ACR.