Automatic charge relay ML-ACR - 12 V DC 500 A

The BLUE SEA ML-ACR 500A (part number PN 7620) is a rugged automatic charging relay designed for demanding marine and automotive applications. It manages two battery banks by automatically combining them during charging and isolating them when no charging is detected. This model can handle high-efficiency alternators and large battery banks thanks to its continuous 500-amp capacity.

Magnetic Latching (ML) technology is a key feature of the ML-ACR 500A relay. It ensures extremely low current draw when the relay is in the ON or OFF state. The relay only draws moderate current during the very brief period when it changes state (approximately 20 ms), which optimizes battery life by reducing continuous current draw.

The ML-ACR 500A provides configurable isolation functions to protect sensitive onboard electronics:

Start Isolation (SI): Temporarily protects 12V service loads from engine circuit voltage drops and surges during engine start-up.Engine Isolation (EI): Allows isolation of two engines in operation to protect their electronics and maximize alternator output.

Note: The ML-Series ACR can be configured for Start Isolation or Engine Isolation, but not both simultaneously.

The ML-ACR 500A relay automatically combines battery banks when the detected voltage reaches:

Above 13.5V for 30 secondsAbove 13.0V for 90 secondsIt automatically isolates battery banks when the detected voltage drops to:

Below 12.35V for 10 secondsBelow 12.75V for 30 seconds

The ML-ACR 500A relay integrates protections against extreme voltages for 12V DC operation:

Undervoltage Lockout: Prevents battery combining when one battery is below 9.6V. Overvoltage Lockout: Prevents battery combining when one battery is above 16.2V. These mechanisms protect the relay from overvoltages and high peak currents, as well as batteries from excessive discharge or overcharging.

Yes, the ML-ACR 500A relay is designed for durability in harsh environments. It is rated IP66, meaning it is protected against dust and powerful water jets. Additionally, it features tinned copper studs for maximum conductivity and corrosion resistance, as well as silver alloy contacts for high reliability when switching loads under load.

No, the ML-ACR 7620-BSS model is designed for fully automatic operation and does not include integrated manual control. The PN 7622 and PN 7623 models in the ML-ACR series are the ones that feature manual control.

The ML-ACR 500A relay control circuit draws less than 40 mA.

The standard ML-ACR 500A (PN 7620) is optimized for AGM/GEL to AGM/GEL or AGM/GEL to Lithium battery configurations. For systems using lithium batteries in Lithium to Lithium or Lithium to Lead-Acid configurations, the ML-ACR Li-Ion version is recommended, specifically designed for these applications.

No, the ML-ACR 500A model (PN 7620) is specifically designed for 12V DC systems. Other models in the ML-ACR series (e.g., PN 7621 or PN 7623) are designed for 24V DC systems.

Yes, the ML-ACR 500A is designed to support high-efficiency alternators and large battery banks. Its continuous 500A capacity allows it to efficiently manage power distribution and optimize charging performance even under demanding conditions.

The ML-ACR 500A can be remotely controlled using a Contura switch (SPDT) with three positions (ON-OFF-AUTO). This type of switch allows forcing battery bank combinations, isolating them, or letting the relay operate in automatic mode. A momentary switch (SPDT) (ON)-OFF-(ON) or a momentary push button can also be used to ensure cross-connection and/or battery isolation.

To ensure the ML-ACR 500A relay reaches its continuous rated capacity of 500A, it is recommended to use 2x 4/0 AWG (2x 120 mm²) cable. This wiring will handle a starting current of 1450A (30 sec) and an intermittent current of 700A (5 min).

The ML-ACR 500A is equipped with 3/8"-16 terminal studs. The recommended maximum tightening torque for these studs is 140 in-lb (15.8 N•m). It is important to respect this torque to ensure a secure connection and avoid damaging the relay.

The ground wire of the ML-ACR 500A must be connected to a common ground or directly to the battery's negative terminal. A proper ground connection is essential for the relay to function correctly.

The ML-ACR 500A relay provides a remote LED output to indicate the battery status. If the remote switch LEDs are off, the batteries are isolated. If the LEDs are on, the batteries are combined. Specific LED flashing patterns also indicate states such as start/engine isolation, undervoltage lockout, or overvoltage.

The physical dimensions of the ML-ACR 500A relay are as follows:

Width: 3.75" (95.3 mm)Height: 5.47" (138.9 mm)Depth: 2.03" (51.6 mm)

Configuration of Start Isolation (SI) or Engine Isolation (EI) depends on how the inputs are wired. The detailed instructions provided with the product describe the specific wiring diagrams for each function. It is important to note that the relay can be configured for either of these functions, but not both simultaneously.

Yes, the ML-ACR 500A relay is ignition-protected. It is certified to meet external ignition protection requirements per ISO 8846 and SAE J1171 standards, making it safe for use in engine compartments where flammable vapors may be present.