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REDARC Electronic Dual Battery Isolator (SBI12) vs Victron Energy Cyrix-ct 12/24V Intelligent Battery Combiner

Buy the Victron Cyrix-ct for most dual-battery builds. It costs far less, handles 12V and 24V, and adds a 30-second start assist. The REDARC SBI12 is the pick only for a simple 12V 4WD or commercial setup that wants a sealed, overmoulded unit with LED fault indication. On price, the Cyrix-ct is $46.83 at RV Parts Giant and the SBI12 is $141.99 at jeepandtruckparts.com, both as of November 3, 2026.

Today the Victron Energy Cyrix-ct 12/24V Intelligent Battery Combiner costs $95.16 less at its best price.

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REDARC
REDARC Electronic Dual Battery Isolator (SBI12)

REDARC Electronic Dual Battery Isolator (SBI12)

$141.99at jeepandtruckparts.comObserved at 7:44 AM

Choose the REDARC SBI12 if you run a 12V-only 4WD or work vehicle and want a sealed, surge-protected isolator with LED fault indication and silver contacts.

Pros
  • Sealed overmoulded aluminum body resists dust and vibration
  • LED warns of voltage drop, over-voltage and excessive current
  • Silver contacts and full surge protection
  • Simple 12V install for 4WD and commercial dual-battery systems
Cons
  • 12V only, no 24V support
  • 100A continuous is below the Cyrix-ct

What separates them

REDARC Electronic Dual Battery Isolator (SBI12)Victron Energy Cyrix-ct 12/24V Intelligent Battery Combiner
Price (best new)$141.99 at jeepandtruckparts.com as of November 3, 2026$46.83 at RV Parts Giant as of November 3, 2026
System voltage12V DC only12V or 24V
Continuous current100A120A
Cranking / short surge100A max alternator output180A for 5 seconds
Start assistNoneYes, stays engaged 30 seconds
Standby drawLow standby draw, figure not published4 mA open, 220 mA closed at 12V
Housing and sealingOvermoulded aluminum, fully surge protectedIP54 rated, 0.1 kg

Price history

  • REDARC Electronic Dual Battery Isolator (SBI12): lowest $151.63 on Nov 3 at Explosive Powersports.
  • Victron Energy Cyrix-ct 12/24V Intelligent Battery Combiner: lowest $39.44 on Nov 3 at Voltaico.

Prices at every store

REDARC Electronic Dual Battery Isolator (SBI12)

  • jeepandtruckparts.comNew

    In stockReturn policy

    $141.99Observed at 7:44 AM
    Visit store
  • WalmartNew

    In stockSold by UnbeatableSale

    $165.00Free shippingObserved at 7:44 AM
    Visit store
  • Explosive PowersportsNew

    In stock

    $151.63+ $27.09 shippingObserved at 7:44 AM
    Visit store
  • AmazonNew

    Availability unknown

    $165.00Free shippingObserved at 7:44 AM
    Visit store

Also available at

  • eBayCheck price at eBay
  • ZoroCheck price at Zoro

Specs compared

SpecREDARC Electronic Dual Battery Isolator (SBI12)Victron Energy Cyrix-ct 12/24V Intelligent Battery Combiner
Continuous current100A120 A
Height2.480 in.46 mm
Voltage12V DC—
Standby current drawlow standby current draw—
Fault indicationLED indication of operation—
Surge protectionFully surge protected—
Contact materialSilver contacts—
Housing designOvermould design—
Maximum alternator output100 amps—
Length3.150 in.—

Questions and answers

Which is better for a 24V truck or boat?
The Victron Cyrix-ct. It handles 12V or 24V, while the REDARC SBI12 is 12V only.
Is the REDARC worth the extra money?
Only if you need its LED fault indication and sealed overmoulded body on a 12V system. The Cyrix-ct does more for about $95 less.
Which handles more current?
The Cyrix-ct: 120A continuous and 180A for 5 seconds, against 100A continuous for the SBI12.
Will the Cyrix-ct work with a smart alternator?
It closes at 13.0 to 13.8V. A smart alternator that runs below 13.0V may never trigger it, so check your charging voltage first.
Which draws less power when idle?
The Cyrix-ct draws 4 mA when open. REDARC calls the SBI12 draw low but does not publish a figure.
Can either help start the engine from the auxiliary battery?
Only the Cyrix-ct. Its start assist keeps it engaged for 30 seconds. The SBI12 has no start assist.

More comparisons

  • REDARC Electronic Dual Battery Isolator (SBI12) vs Blue Sea Systems Add-A-Battery Kit 120A Dual Circuit System, 7650
  • REDARC Electronic Dual Battery Isolator (SBI12) vs Stinger SGP35 High Current 500-Amp Battery Relay & Isolator
  • REDARC Electronic Dual Battery Isolator (SBI12) vs Blue Sea Systems Automatic Charging Relay (ACR) 7610
  • Victron Energy Cyrix-ct 12/24V Intelligent Battery Combiner vs Blue Sea Systems Automatic Charging Relay (ACR) 7610

Buying guides that pick them

  • Best dual battery isolators
No start assist
  • Costs about $95 more than the Cyrix-ct
    • Victron Energy
    Victron Energy Cyrix-ct 12/24V Intelligent Battery Combiner

    Victron Energy Cyrix-ct 12/24V Intelligent Battery Combiner

    $46.83at RV Parts GiantObserved at 7:44 AM

    Choose the Victron Cyrix-ct if you want a cheaper combiner that works on 12V or 24V, handles 120A continuous with 180A cranking, and offers a 30-second start assist.

    Pros
    • Works on 12V and 24V systems
    • 120A continuous and 180A for 5 seconds
    • 30-second start assist helps a flat start battery
    • Very low 4 mA draw when open
    • IP54 rated and weighs only 0.1 kg
    Cons
    • Needs 13.0 to 13.8V to close, so a low-running smart alternator may never trigger it
    • 220 mA draw while closed at 12V
    • Status LED only on the 230A model
    • Best suited to lead-acid house batteries, not lithium
    Status indication
    LED fault indication (voltage drop, over-voltage, over-current)
    Status LED on 230A model only
    All 6 stores and price history →

    Victron Energy Cyrix-ct 12/24V Intelligent Battery Combiner

    • RV Parts GiantNew

      In stock

      $46.83Free shippingObserved at 7:44 AM
      Visit store
    • WalmartNew

      In stockSold by KFN Tech

      $49.30Free shippingObserved at 7:44 AM
      Visit store
    • eBayNew

      In stock

      $49.30Free shippingObserved at 7:44 AM
      Visit store
    • VoltaicoNew

      In stock

      $39.44+ $18.00 shippingObserved at 7:44 AM
      Visit store
    All 6 stores and price history →
    Width
    2.950 in.
    —
    MaterialAluminum—
    Show all 22 specsShow fewer specs
    SpecREDARC Electronic Dual Battery Isolator (SBI12)Victron Energy Cyrix-ct 12/24V Intelligent Battery Combiner
    Nominal Battery Voltage—12V or 24V
    Cranking Current Rating—180 A
    Current Consumption Open—4 mA
    Current Consumption Closed12—220 mA
    Current Consumption Closed24—120 mA
    Start Assist—Yes (Cyrix remains engaged during 30 seconds)
    Battery Terminals—M6 bolts
    Start Assist Terminal—Faston tab 6.3 mm
    Protection Category—IP54
    Weight—0.1 kg