Automatic charge relay ML-ACR with manual control - 12 V DC 500 A

The Blue Sea Systems ML-ACR (Automatic Charging Relay) is a device designed to manage high-demand battery systems. It automatically combines and isolates battery banks, ensuring efficient charge distribution with very low current draw whether the relay is ON or OFF. This model is specifically designed for 12V DC systems with a continuous capacity of 500A.

This ML-ACR relay has a continuous current rating of 500 amperes (A). It can also handle an intermittent current of 700A for 5 minutes and a cranking rating of 1450A for 30 seconds when wired with 2x 4/0 AWG (2x 120 mm²) cables.

Yes, the ML-ACR relay is designed to be robust and durable in harsh environments. It is rated IP66, meaning it is protected against powerful water jets and dust, making it ideal for marine and automotive applications.

Magnetic Latching (ML) technology allows the relay to maintain its state (ON or OFF) without continuous power consumption. It only draws a moderate current for a very brief period during state changes, significantly reducing the system's overall energy consumption.

Yes, this ML-ACR relay model (PN 7622) is supplied with a Contura remote control switch (SPDT ON-OFF-ON type), allowing manual control of the relay functions from a convenient location such as the helm station.

The ML-ACR relay integrates two advanced isolation functions:

Start Isolation (SI): Temporarily isolates house loads from the engine circuit during engine start, protecting sensitive electronics from voltage drops.Engine Isolation (EI): Can be configured to isolate two engines in operation, protecting engine electronics and optimizing alternator output.Note that the ML-ACR can be configured for either of these functions, but not both simultaneously.

To achieve the continuous 500A rating of this relay, wiring of 2x 4/0 AWG (2x 120 mm²) is recommended. This sizing ensures maximum conductivity and optimal performance under high loads.

The maximum recommended torque for 3/8"-16 (M10) terminal studs is 140 in-lb (15.8 N•m). It is critical to adhere to this specification to ensure a secure electrical connection and prevent damage to the relay.

The physical dimensions of the ML-ACR relay (model 7622) are as follows:

Width: 95.3 mm (3.75 in)Height: 138.9 mm (5.47 in)Depth: 51.6 mm (2.03 in)Its weight is approximately 0.93 kg (2.04 lb).

Yes, the ML-ACR relay meets the ignition protection requirements of ISO 8846 and SAE J1171, making it safe for use in boat engine compartments where flammable vapors may be present.

In automatic mode (for a 12V DC system), the relay combines battery banks when the detected voltage reaches:

More than 13.5V for 30 seconds, orMore than 13.0V for 90 seconds.This ensures batteries are only combined when a load is present and stable.

In automatic mode (for a 12V DC system), the relay isolates the battery banks when the detected voltage drops below:

12.35V for 10 seconds, or 12.75V for 30 seconds. This protects the batteries from excessive discharge and ensures one bank remains available for starting.

The standard ML-ACR relay (reference 7622B-BSS) is optimized for AGM/GEL to AGM/GEL and AGM/GEL to lithium battery configurations. However, it is not specifically designed for lithium-to-lithium or lithium-to-lead-acid systems due to predefined voltage thresholds. For full compatibility with lithium battery systems, the ML ACR Li-Ion version is recommended.

The ML-ACR relay includes protections against extreme voltages:

Undervoltage lockout: The relay prevents battery combining if the voltage of one battery is below 9.6V (for a 12V DC system). Overvoltage lockout: The relay prevents battery combining if the voltage of one battery is above 16.2V (for a 12V DC system). These thresholds protect the relay and batteries against hazardous conditions.

No, this specific model of the ML-ACR automatic charge relay (reference 7622B-BSS) is designed and rated to operate only with 12V DC systems. Other models in the ML-ACR series are compatible with 24V DC systems, but this one is not.

The Magnetic Latching (ML) technology ensures very low current consumption. In ON or OFF state, the relay consumes less than 13mA at 25°C and nominal voltage (12V DC). During state change, consumption is moderate, but only for about 20 milliseconds.

The relay contacts are made of silver alloy, ensuring high reliability for switching loads under voltage. The terminal studs are 3/8"-16 (M10) tin-plated copper, providing maximum conductivity and excellent corrosion resistance in marine environments.

The remote control switch has two LEDs that indicate the relay status:

LEDs off: Batteries are isolated.LEDs on: Batteries are combined.Slow, regular flashing: Start isolation (SI) or engine isolation (EI) is active.Fast, regular flashing: Undervoltage lockout (below 9.6V) or overvoltage lockout (above 16.2V).Double flash (Blink-Blink-Pause): Indicates manual control or a mechanical relay failure.

Although both are isolation functions, they serve different purposes:

Start Isolation (SI): Temporarily isolates the house loads from the engine circuit during engine start. This protects sensitive electronics from voltage drops and spikes that can occur during engine start.

Engine Isolation (EI): Isolates two engines when both are running. This is useful for protecting the electronics of each engine and optimizing the output of each alternator, especially when engine manufacturers require it or when each engine has its own starter battery.

The ML-ACR can be configured for either of these functions, but not both simultaneously.