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ML-ACR Automatic Charging Relay – 12V DC 500A



500 Amp magnetic latching (bi-stable) relay automatically combines batteries during charging and isolates batteries when discharging and when starting engine

  • ML-Series Remote Control Contura Switch PN 2146 available as a seperate item
  • 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


Control Circuit ConnectionTinned Wire
Nominal Voltage12V DC
Manual ControlNo
Engine IsolationYes
Start AssistYes
Start IsolationYes
Amperage Operating Current13mA
Amperage Operating Current when changing state<7.0A
Terminal Stud Torque140 in-lb (15.82 Nm)
Continuous Rating500A
Intermittent Rating700A (5 min)
Cranking Rating 10 sec2500A
Cranking Rating 1 min1100A
Cable Size to Meet Ratings4/0 AWG x 2
Live Current Switching300A @ 12V DC
Switching Cycles100000
Terminal Ring Diameter Clearance1.12in (28.45 mm)
Terminal Stud Length1.50in (38.1 mm)
Terminal Stud Size3/8″ – 16 (M10)
Wire Size20 AWG
Relay Contact Position
Combine 30 sec13.5V
Combine 90 sec13.0V
Open 10 sec12.35V
Open 30 sec12.75
Open High16.2V
Weight0.93 kg