VICTRON ENERGY ▶ CYRIX-CT SERIES Victron Cyrix-ct 120A 12/24V Intelligent Battery Combiner Automatic Voltage Sensing | Bi-Directional Charging | 12V/24V Systems The Victron Cyrix-ct 120A 12/24V Intelligent Battery Combiner (SKU: CYRIX-120A) is a microprocessor-controlled heavy-duty relay designed to automatically connect and disconnect two independent battery banks. This intelligent device optimises power sharing between batteries, ensuring efficient charging without the risk of over-discharging either bank. It serves as an excellent replacement for traditional diode isolators, offering virtually no voltage loss for enhanced charging efficiency. Ideal for vehicle battery systems, the Cyrix-ct 120A allows an alternator to charge both the engine starter battery and a leisure battery. Conversely, it enables charging from solar power or mains hook-up to be shared with the engine starter battery, providing flexible and reliable power management for various applications. IMPORTANT COMPATIBILITY: Both battery banks in the system must have the same rated voltage (12V or 24V) for optimal performance. Key Features ▶ Intelligent Battery Monitoring — Prevents unwanted switching by analysing voltage trends. ▶ Automatic Voltage Detection — Automatically adjusts for 12V or 24V system voltages. ▶ Bi-Directional Voltage Sensing — Connects batteries if either bank receives charge from any source. ▶ Zero Voltage Loss — Replaces diode isolators with virtually no voltage drop, improving charging efficiency. ▶ Start Assist Function — Allows manual override to combine batteries for emergency engine starting. ▶ Overheating Protection — Disengages in case of excessive contact temperature, re-engaging once cooled. Technical Specifications Parameter Value Rated Voltage 12V / 24V Auto Detect Continuous Current 120A Cranking Current (5 secs) 180A Standby Consumption <4mA Terminal Size M8 (main terminals) Protection Category IP54 Dimensions (H x W x D) 46 x 46 x 80 mm Weight 0.11 kg (110g) Operating & Power Guidance The Cyrix-ct 120A acts as a smart relay, connecting batteries in parallel when one reaches a pre-set voltage (indicating it's being charged) and disconnecting them when the voltage drops below float level (indicating discharge). This intelligent behaviour prevents unwanted switching and ensures efficient power distribution. Its bi-directional sensing means that if either battery bank is receiving a charge (e.g., from an alternator, solar charger, or mains hook-up), the Cyrix-ct will engage to allow both banks to be charged. This maximises the use of available charging sources. For emergency situations, the Start Assist function allows you to temporarily combine the battery banks via a push button. This can provide crucial extra power to start an engine if the primary starter battery is discharged or damaged. Typical Applications Application Description Motorhomes & Caravans Efficiently links starter and leisure batteries for shared charging from the alternator or shore power. Boats & Marine Vessels Manages charging between engine start batteries and house batteries, ensuring reliable power at sea. Off-Grid Systems Connects multiple battery banks for charging from solar or wind, optimising energy storage. Commercial Vehicles Ensures auxiliary batteries for equipment are charged alongside the main starter battery. Built-In Protection Functions The Victron Cyrix-ct 120A is designed with robust protection features to ensure system safety and longevity. It includes intelligent battery monitoring to prevent unwanted switching due to short, high-amperage loads or immediate voltage drops from large discharged banks. The unit also features protection against overheating, disengaging in case of excessive contact temperature caused by prolonged overload and re-engaging once it has cooled down to a safe operating temperature. This ensures reliable and safe operation across various demanding applications. Common Questions What is the primary function of the Cyrix-ct 120A? The Cyrix-ct 120A is an intelligent battery combiner that automatically connects and disconnects two battery banks in parallel. It ensures that both batteries are charged efficiently from a single source (like an alternator or solar charger) and prevents discharge of the starter battery by the auxiliary battery. Can it be used with different voltage batteries? No, the Victron Cyrix-ct 120A is designed for systems where both battery banks have the same rated voltage, either 12V or 24V. It automatically detects the system voltage but requires consistency between the connected banks. Is the Cyrix-ct 120A compatible with Euro 6 engines? Smart alternators found in Euro 6 or later engines may not be fully compatible with Voltage Sensing Relay technology, such as that used by this battery combiner. It is recommended to verify compatibility with your vehicle's specific alternator type before purchase. How does the Start Assist function work? The Start Assist function allows for manual engagement of the Cyrix-ct, connecting both battery banks in parallel for approximately 30 seconds. This provides a temporary boost from the auxiliary battery to help start the engine if the main starter battery is low or discharged. Installation Notes Install the Cyrix-ct between the positive terminals of the two batteries or battery banks. Ensure appropriate fuses are wired into the positive cables connected to the unit's bolt terminals. The negative terminals of both batteries should be directly linked or connected through a common negative ground (e.g., vehicle chassis). Connect the battery common negative to the Cyrix-ct's negative input using a thin cable (not provided). Always refer to the detailed user manual supplied with the product for comprehensive wiring diagrams and operational instructions. Professional installation is recommended to ensure correct and safe operation. Before You Buy Verify that both battery banks in your system operate at the same nominal voltage (12V or 24V). Consider the total continuous current draw and cranking current requirements of your system to ensure the 120A rating is sufficient. Check for compatibility with modern vehicle alternators, especially Euro 6 or later engines, as Voltage Sensing Relays may not be suitable. Ensure you have the necessary cabling, fuses, and tools for installation, as these are not typically included. Consult the manufacturer's documentation for detailed technical specifications and installation guidelines. Please verify all specifications and compatibility requirements with your specific system before purchase. This product is covered by a 5-year manufacturer warranty.
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