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Blue Sea Systems SI-ACR Automatic Charging Relay

Product Description

Automatically manages the charging of two battery banks and can be configured for temporary isolation of House loads from Engine circuit during engine cranking to protect sensitive electronics. Rated at 120A continuous and supports high-output alternators. Built in LED light indicates when batteries are combined and blinks when the under voltage or the starting isolation feature is engaged.

Clip-on cover protects terminal connections. 12/24V auto ranging voltage
input. Hermetically sealed contacts/vapor-proof. Ignition protected, Safe for
installation aboard gasoline powered boats. Meets UL 1500, SAE J1171 external
ignition protection requirements and is IP67 certified for temporary immersion
for 30 minutes.

Automatically combines batteries during charging, isolates batteries when discharging and when starting engines


  • Protects sensitive electronics by temporary isolation of house loads from engine circuit during engine cranking
  • Designed for 12 or 24 volt systems
  • 12/24 volt auto ranging voltage input
  • Hermetically sealed contacts/vapor proof
  • Ignition protected—safe for installation aboard gasoline powered boats
  • Supports high-output alternators up to 120 Amperes
  • Dual sensing

Optional Features

  • Start Isolation allows temporary isolation of House loads from Engine circuit during engine cranking to protect sensitive electronics from sags and spikes
  • Remote LED remotely indicates ACR states - requires optional LED
Nominal Voltage 12V DC
24V DC
Start Isolation  Yes
Amperage Operating Current 175mA (combined)
15mA (open)
Terminal Stud Torque 140 in-lb (15.82 Nm)
Continuous Rating  120A
Intermittent Rating  210A (5 min)
Cable Size to Meet Ratings 1/0 AWG
Stud Material Tinned Copper
Terminal Ring Diameter Clearance 1.12in (28.45 mm)
Terminal Stud Length 0.875in (22.23 mm)
Terminal Stud Size 3/8" - 16 (M10)
Combine 30 sec 13.6V @ 12 V
27.2V @ 24 V
Combine 90 sec 13.0V @ 12 V
26.0V @ 24 V
Open 10 sec 12.35V @ 12 V
24.7V @ 24 V
Open 30 sec 12.75V @ 12 V
25.5V @ 24 V
Open High 16.0V @ 12 V
30.0V @ 24 V
Over Voltage Lockout 16.0V @ 12V
32.0V @ 24V
Under Voltage Lockout  9.5V @ 12 V
19V @ 24 V
Weight 1.25lb (0.57 kg)



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