Three ACRs from Blue Sea Systems

January, 01 2005
This resource is only available for historical purposes. As such it is no longer maintained and may contain errors, inconsistencies or no longer hold relevancy.

Automatic Charging Relays (ACRs) combine batteries during charging, and isolate batteries when not charging. Blue Sea Systems provides three automatic charging relays with a wide range of current ratings for most applications:

  • 60 Amp BatteryLink™ ACR
  • 120 Amp SI ACR
  • 450 Amp ACR

All three Blue Sea Systems' ACRs share these features:

  • Ignition protection-safe for installation aboard gasoline powered boats
  • Dual sensing-senses charging on either battery bank
  • Large tin-plated copper studs for high conductivity and maximum corrosion resistance

This diagram represents a typical ACR installation.

60A BatteryLink™ ACR (Part Number: 7600)

These features are unique to the 60A BatteryLink™ ACR.

  • Current limiting allows for wire size adequate for charging currents without the need to oversize wires for high load currents. Current limiting solves some wire-sizing problems in a way that takes into account voltage drop, charge acceptance curves, etc. Current limiting saves money and weight by allowing for the use of smaller gauge wire.
  • User-adjustable open and close voltage settings designed to meet the charging and electrical needs of individual boaters.

120A SI ACR (Part Number: 7610)

These features are unique to the 120Amp SI ACR.

  • Allows temporary isolation of house and starting batteries during engine cranking to protect sensitive electronics and other loads connected to the house battery, and to assure that only the starting battery is used to start the engine.
  • Waterproof rated IP67-temporary immersion for 30 minutes. Use on bridge deck or other wet locations. The waterproof design makes this the unit of choice for all open and semi-open boats.
  • Under voltage lockout -- will not close when the lower voltage battery is below about 9.5V (in 12V operation) or 19V (in 24V operation). Prevents an automatic connection to a defective battery bank.
  • Supports high-output alternators up to 120 Amperes.
  • Sensing circuit requires very low current draw when contact is closed.

450A ACR (Part Number: 9112)

These features are unique to the 450A ACR.

  • Sensing circuit requires very low current draw when contact is closed.
  • Override for emergency battery bank combining to start an engine. In addition to charge management, the 450A ACR is robust enough to use as an emergency cross connect for engine starting.

ACRs can be used for load shedding, pilot house navigation battery isolation, and charge current limiting for a remote battery. Click for descriptions of each application.

Comparison of the three ACRs

ACR Part Number12V, 24VContinuous Current RatingDual or Single SensingDistinguishing Features
760012V60ADual or Single Sensing
  • Adjustable high, low, and combine voltages
  • Current limiting
761012V, 24V120ADual Sensing
  • Waterproof to IP-67 (immersion for 30 minutes)
  • Isolates batteries during engine cranking
  • Under voltage lockout
911212V, 24V450ADual or Single Sensing
  • Combines batteries for emergency starting (with optional switch)
  • HIgh current carrying
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