500 Amp magnetic latching (bi-stable) relay automatically combines batteries during charging and isolates batteries when discharging and when starting engine
  • Includes ML-Series Remote Control Contura Switch PN 2146
  • Automatically manages the charging of two large battery banks
  • Allows paralleling of battery banks for emergency starting
  • 500 Ampere continuous rating to support high-output alternators
  • Magnetic Latch (ML)—ACR draws very low current (<40mA to monitor terminal voltage) in the "ON" or "OFF" states, and draws moderate current for very short time when changing state
  • Dual sensing—senses charge on both battery banks
  • Start Isolation (SI)—can be configured for temporary isolation of House loads from Engine circuit during engine cranking to protect sensitive electronics
  • Engine Isolation (EI)—can be configured for isolation of two engines while both are running to protect engine electronics and maximize alternator output
  • Senses charging on two battery banks
  • LED output to remotely indicate when batteries are combined, isolated, in voltage lockout, or in Start or Engine isolation
  • 3/8"-16 tin-plated copper studs for maximum conductivity and corrosion resistance
  • 7/8" (22mm) stud length accepts multiple cable terminals
  • Silver alloy contacts provide high reliability for switching live loads
  • Label recesses for circuit identification


Nominal Voltage 24V DC
Control Circuit Connection (1) Yes
Manual Control (2) No
Engine Isolation (3) Yes
Start Assist (4) Yes
Start Isolation (5) Yes
Amperage Operating Current (@ 25°c nominal) 13mA
Amperage Operating Current when changing state <7.0A
Continuous Rating (6) 500A
Intermittent Rating
700A (5 min.)
Cranking Rating 10 sec. (7) 2500A
Cranking Rating 1 min. (8) 1100A
Cable Size to Meet Ratings
4/0 AWG x 2
Live Current Switching
300A @ 12V DC
Switching Cycles 100,000
Terminal Ring Diameter Clearance
1.12in (28.45 mm)
Terminal Stud Length
1.50in (38.1 mm)
Terminal Stud Size
3/8-16 (M10)
Terminal Stud Torque
140 in-lb (15.82 Nm)
Relay Contact Position
Combine 30 sec. 27.0V
Combine 90 sec. 26.0V
Open 10 sec. 24.7V
Open 30 sec. 25.5V
Open High 32.4V
Weight 2.08lb (0.94 kg)

1) Manual control switch provides an added level of safety allowing control with or without power, and offering LOCK OFF capability for servicing.

2) Condition: Two engines are running

  • One relay is open and one relay is closed
  • Engine 1 Start and Engine 2 Start batteries are isolated to protect engine electronics

3) Condition: Engine starting

  • Relay is closed combining batteries
  • Batteries are combined to share power in the event of a low start battery

4) Condition: Engine starting

  • Relay is open isolating batteries
  • Batteries are isolated to protect sensitive electronics from voltage sags and spikes

5) The maximum current a switch is designed to conduct for an indefinite period.

6) The maximum amount of current a switch is designed to carry for a minimum of a designated period of time.

7) Normally associated with 'cranking current' which is the current required by the starter circuit prior to engine starting. The cranking current varies significantly during the starting cycle. Initially, there is a large surge of current required to overcome the inertia and compression of the engine. This surge can be two to four times the average cranking current. Once the engine is turning there are peaks and valleys as the pistons go through the compression and exhaust cycles. The cranking current rating is used for sizing batteries, cables, and battery switches.

8) The maximum amount of current a switch is designed to carry when starting an engine when the cranking period does not exceed 1 minute.

SKU 632085076238
Barcode # 7623-BSS
Brand Blue Sea Systems
Shipping Weight 1.0000kg
Shipping Width 0.280m
Shipping Height 0.090m
Shipping Length 0.170m
Shipping Cubic 0.004284000m3

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