Blue Sea 7621 – ML-ACR Automatic Charging Relay 24V DC 500A with Remote Control Switch

ID 1001824

1-2 weeks delivery time

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The Blue Sea 7621 ML-ACR is a 24V DC magnetic latching Automatic Charging Relay rated 500A continuous, 700A (5 min) and 1450A cranking (30 sec) for automatic combining and isolation of two large battery banks. It features dual sensing, start isolation, engine isolation, and start assist functions, with low holding current (13mA nominal) and <7A during state change. Built with 3/8"-16 (M10) tinned copper studs with 1.50" length, supports 4/0 AWG x2 cable, switching cycles 100,000, operating range −10°C to +60°C, and includes SPDT Remote Control Contura Switch PN 2146.

Description
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Blue Sea 7621 – ML-ACR Automatic Charging Relay 24V DC 500A with Remote Control Switch

The Blue Sea 7621 ML-ACR Automatic Charging Relay is a 24V DC magnetic latching (bi-stable) relay designed to automatically combine battery banks during charging and isolate them during discharge and engine starting. It is built for high-current systems and supports automatic charging management of two large battery banks.

The magnetic latch design provides very low current draw while monitoring terminal voltage and only draws higher current for a very short time when changing state. The relay supports dual sensing, start isolation, engine isolation, and start assist functions. A remote control Contura switch (PN 2146) is included.

Key Features

Magnetic latching (bi-stable) Automatic Charging Relay
24V DC system design
Automatically combines batteries during charging and isolates during discharge
500A continuous rating for high-output alternator systems
Dual sensing on both battery banks
Emergency battery paralleling for engine starting
Start Isolation (SI) for protection of sensitive electronics
Engine Isolation (EI) for twin-engine installations
Low holding current draw in ON/OFF states
LED output for remote status indication
Silver alloy contacts for switching live loads
Label recesses for circuit identification

Included

Qty	PN	Description
1	2146	SPDT Remote Control Contura Switch – ON-OFF-ON

Electrical Ratings

Nominal Voltage	24V DC
Continuous Rating	500A
Intermittent Rating	700A (5 min)
Cranking Rating	1450A DC (30 sec)
Operating Current	13mA @ 25°C nominal VDC
Operating Current (state change)	<7.0A
Live Current Switching	300A @ 12V DC

Voltage Thresholds

Combine (30 sec)	27.0V
Combine (90 sec)	26.0V
Open (10 sec)	24.7V
Open (30 sec)	25.5V
Open High	32.4V

Isolation & Assist Functions

Start Assist: relay closes to combine batteries during engine starting if needed
Start Isolation: relay opens to isolate house loads during cranking
Engine Isolation: isolates start batteries in twin-engine installations

Connections & Mounting

Control Circuit Connection	Tinned Wire
Mounting	#10
Terminal Stud Size	3/8"-16 (M10)
Stud Length	1.50 in (38.1 mm)
Stud Material	Tinned Copper
Terminal Ring Clearance	1.12 in (28.45 mm)
Terminal Stud Torque	140 in-lb (15.82 Nm)
Cable Size to Meet Ratings	4/0 AWG x 2
Control Wire Size	20 AWG