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Blue Sea Systems Automatic Charging Relay vs REDARC SBI12 Battery Isolator

These are not substitutes. The Blue Sea ACR is a 24V, 210A automatic charging relay for combining and isolating battery banks, built for gasoline boats with an ignition-protected, IP67 sealed housing. The REDARC SBI12 is a 12V, 100A microprocessor-controlled isolator aimed at vehicle dual-battery systems, with LED fault indication and low standby draw. Buy the Blue Sea for a 24V marine bank; buy the REDARC for a 12V truck, camper or 4WD.

  • Choose the Blue Sea Systems ACR if your system runs 24V and you need a high-current, ignition-protected, sealed relay for a gasoline boat.
  • Choose the REDARC SBI12 if you run a 12V vehicle and want a compact, microprocessor-controlled isolator with fault LEDs and low standby draw.

Prices

  • Blue Sea Systems Automatic Charging Relay: $84.81 at Amazon (last seen Nov 10)
  • REDARC SBI12 Battery Isolator: $131.00 at Upfitters (last seen Nov 10)
  • Difference: the Blue Sea Systems Automatic Charging Relay is $46.19 cheaper than the REDARC SBI12 Battery Isolator at the latest prices (Nov 10)
Blue Sea Systems
Blue Sea Systems Automatic Charging Relay

Blue Sea Systems Automatic Charging Relay

$84.81at AmazonChecked Nov 10
See all prices and details
Visit Amazon

Store links may earn us a commission. As an Amazon Associate, Deal.ai earns from qualifying purchases.

Pros
  • High 210A intermittent rating for large banks
  • IP67 and vaporproof for wet marine installs
  • Ignition protected for gasoline engine compartments
  • 90-second combine delay avoids chatter
Cons
  • 24V only, so it will not work in a 12V system
  • No fault LED or microprocessor logic
  • Continuous rating is not stated
  • Coil draw is higher than a smart isolator
REDARC
REDARC SBI12 Battery Isolator 12 Volt 100A

REDARC SBI12 Battery Isolator

REDARC SBI12 Battery Isolator 12 Volt 100A

$131.00at UpfittersChecked Nov 10
See all prices and details
Visit Upfitters
Pros
  • Microprocessor control with clear on/off thresholds
  • LED fault indication helps diagnose wiring
  • Low standby current draw
  • Compact and light, easy to mount in a vehicle
  • 400A inrush handles startup surges
Cons
  • 100A continuous limits large auxiliary banks
  • 12V only
  • No IP67 or ignition protection rating listed
  • No adjustable combine delay listed

What separates them

Blue Sea Systems Automatic Charging RelayREDARC SBI12 Battery Isolator
System voltage24V DC only12V only
Current rating210A intermittent (5 min)100A continuous, 400A inrush
ControlVoltage-sensing relay with 90-second combine delayMicroprocessor-controlled with 12.7V off and 13.2V on thresholds
Fault feedbackNone listedLED indication of operation and faults
Sealing and ignition protectionIP67, vaporproof, ignition protectedNot specified as sealed or ignition protected
Standby drawCoil-powered, no low-draw mode listedPower-saving technology with low standby current
Mounting and sizePanel mount, stud terminalsCompact 75 x 63 x 80 mm, about 0.2 kg
Intended useGasoline-powered boatsVehicle dual-battery systems

Price history

  • Blue Sea Systems Automatic Charging Relay: lowest $84.81 on Nov 10 at Amazon.

Prices at every store

Blue Sea Systems Automatic Charging Relay

  • The Home DepotNew

    In stock

    $93.84Free shippingChecked Nov 10
    Visit The Home Depot
  • Hodges MarineNew

    In stock

    $108.05Free shippingChecked Nov 10
    Visit Hodges Marine
  • Wake WorksNew

    In stock

    $109.97Free shippingChecked Nov 10
    Visit Wake Works
  • AmazonNew

    Availability unknown

    As an Amazon Associate, Deal.ai earns from qualifying purchases.

    $84.81Free shippingChecked Nov 10
    Visit Amazon

Store links may earn us a commission.

All 17 stores and price history →

REDARC SBI12 Battery Isolator

  • HHH Cooling TechnolgiesNew

    In stockShips from Australia · duties may applyReturn policy

    $120.00Checked Nov 10
    Visit HHH Cooling Technolgies
  • UpfittersNew

    In stockReturn policy

    $131.00Checked Nov 10
    Visit Upfitters
  • Gear DealsNew

    In stockShips from Australia · duties may applyReturn policy

    $137.00Checked Nov 10
    Visit Gear Deals
  • Aussie Offroad 4x4New

    In stockShips from Australia · duties may applyReturn policy

    $141.00Checked Nov 10
    Visit Aussie Offroad 4x4
All 18 stores and price history →

Specs compared

SpecBlue Sea Systems Automatic Charging RelayREDARC SBI12 Battery Isolator
Switch TypeAutomatic Charging Relay (ACR)—
Amperage210 A (intermittent rating, 5 min)—
Voltage24V DC—
Current TypeDC—
Coil Voltage24 Volts—
Contact FormNormally Open—
Power Consumption2880.0 W—
CertificationsIgnition protected—
Safety FeaturesIgnition protected—
StandardsAutomotive and Marine Electrical System Standar…—
Degree Of ProtectionIP67 (temporary immersion for 30 minutes)—
Surge ProtectionProtects sensitive electronics from sags and sp…—
Show all 31 specsShow fewer specs
SpecBlue Sea Systems Automatic Charging RelayREDARC SBI12 Battery Isolator
Terminal TypeStud—
Housing TypeHermetically sealed contacts/vaporproof—
Weather ResistanceVaporproof—
Mounting TypePanel Mount—
Connection TypeQuick Connect—
Number Of Connections2—
Operation TypeAutomatic—
Time Delay90 sec (combine)—
ApplicationsGasoline powered boats—
Environments

What reviewers say

Blue Sea Systems Automatic Charging Relay

Owners of this ACR generally report reliable automatic combining and isolation of battery banks, with the sealed, ignition-protected housing trusted in engine compartments. Complaints center on the lack of a manual override and the need to confirm the 24V coil matches the system.

What people mention
  • ReliabilityPraisedOwners say it combines and separates battery banks consistently without fuss.
  • SealingPraisedThe vaporproof, IP67 housing is trusted in damp engine compartments.
  • Manual overrideCriticisedSome wish they could force the banks together, which this model cannot do.
  • VoltageMixedBuyers note the 24V coil must match the system; 12V setups need a different unit.

Questions and answers

Which works in a 24V system?
Only the Blue Sea ACR. The REDARC SBI12 is a 12V unit and should not be used on a 24V bank.
Which handles more current?
The Blue Sea ACR is rated 210A intermittent for 5 minutes. The REDARC is rated 100A continuous with 400A inrush, so it suits smaller loads.
Which is better for a boat?
The Blue Sea ACR. It is ignition protected, IP67 and vaporproof, which matters in a gasoline engine compartment. The REDARC is aimed at vehicle installs.
Which gives better feedback when something fails?
The REDARC. Its LED indicates operation and faults. The Blue Sea ACR has no diagnostic indicator listed.
Is the REDARC worth stepping up to for a 12V truck?
Yes, if you want smart thresholds, fault LEDs and low standby draw in a compact case. The Blue Sea is the wrong voltage for that job.
Does either protect electronics from voltage spikes?
The Blue Sea lists surge protection against sags and spikes. The REDARC does not list surge protection.

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More comparisons

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  • VEVOR Split Charge Relay Kit, 6mtr 12V, 140AMP VSR vs REDARC SBI12 Battery Isolator 12 Volt 100A

Buying guides that pick them

  • Best dual battery isolators
Aboard gasoline powered boats
—
Contact MaterialCopper—
MaterialPlastic—
Voltage System—12 Volt
Max Continuous Current—100 Amps
Max Inrush Current—400 Amps
Off Volts—12.7V
On Volts—13.2V
Dimensions—75L x 63W x 80H
Weight—0.2