Automatic Charging Relays SI-Series

SI-ACR Automatic Charging Relay - 12/24V DC 120A

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/vaporproof
  • 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
MSRP: $124.99
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Nominal Voltage12V DC
24V DC
Start Isolation Yes
Amperage Operating Current175mA (combined)
15mA (open)
Terminal Stud Torque140 in-lb (15.82 Nm)
Continuous Rating 120A
Intermittent Rating 210A (5 min)
Cable Size to Meet Ratings1/0 AWG
Stud MaterialTinned Copper
Terminal Ring Diameter Clearance1.12in (28.45 mm)
Terminal Stud Length0.875in (22.23 mm)
Terminal Stud Size3/8" - 16 (M10)
Relay Contact PositionSPEC_HEADER
Combine 30 sec13.6V @ 12 V
27.2V @ 24 V
Combine 90 sec13.0V @ 12 V
26.0V @ 24 V
Open 10 sec12.35V @ 12 V
24.7V @ 24 V
Open 30 sec12.75V @ 12 V
25.5V @ 24 V
Open High16.0V @ 12 V
30.0V @ 24 V
Overvoltage Lockout16.0V @ 12V
32.0V @ 24V
Undervoltage Lockout 9.5V @ 12 V
19V @ 24 V
Weight1.25lb (0.57 kg)
Included With
7650Add-A-Battery Kit - 120A
7650003Add-A-Battery Kit - 120A [Boxed]
Meets the following Regulatory Specifications
CE Marked
Ignition Protected
ISO 8846
SAE J1171
UL 1500
Previous versions of this product
undervoltage lockout changed (3/2012)
Manual Battery Management and ACR SubSystem

Manual Battery Management and ACR SubSystem

SI-ACR automatically combines batteries during charging, isolates batteries when discharging and when starting engines. The Dual Circuit Plus™ Battery Switch simplifies the switching of two batteries to OFF or ON while still providing battery isolation between the engine and auxiliary battery. The Combine function can be used to parallel the batteries in the event of a low engine battery.

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