Victron Energy - 12/24V - Cyrix-i Intelligent Battery Combiner 12/24V-400A

Victron Cyrix-i 12/24V-400A: Intelligent Battery Combiner for Dual-Battery Systems

Advanced Voltage Sensing and Smart Switching for Reliable Parallel Charging

The Victron Cyrix-i 12/24V-400A is a microprocessor-controlled intelligent battery combiner designed to manage dual-battery systems in vehicles, boats, and off-grid installations. Unlike conventional voltage-sensitive relays (VSRs) that rely on simple voltage thresholds and fixed timers, the Cyrix-i analyses voltage trends to prevent nuisance switching caused by momentary loads or deeply discharged batteries. This ensures your auxiliary battery charges reliably without unnecessary cycling, extending the lifespan of your entire system.

With a continuous current rating of 400 A and a peak capacity of 2000 A, this combiner handles high-demand applications such as winching, bow thrusters, or large inverter loads. The auto-ranging input (8-36 VDC) automatically detects 12V or 24V systems, simplifying installation and reducing inventory complexity for installers.

Why Trend-Based Switching Matters

Standard battery combiners often disconnect under short, high-current loads or fail to engage a depleted battery bank because the voltage collapses below the disconnect threshold. The Cyrix-i overcomes these limitations by evaluating the voltage trend over time. It only reverses a connection if the trend direction changes for a sustained period, preventing false triggers and ensuring stable parallel operation. Four selectable timing profiles allow customisation for different battery chemistries and usage patterns.

Zero Voltage Drop for Maximum Efficiency

Diode-based isolators introduce a forward voltage drop (typically 0.6-0.7 V), requiring higher alternator or charger output voltages and wasting energy as heat. The Cyrix-i uses high-current relay contacts, resulting in virtually no voltage loss. This means your batteries receive the full charging voltage, improving charge efficiency and reducing strain on your alternator or charger.

Bidirectional Sensing and Dual Power Supply

The Cyrix-i monitors voltage on both connected batteries and can be powered from either side. If one battery is too low to operate the relay, the other battery provides the necessary power. This ensures the combiner engages even when the starter battery is deeply discharged, as long as the auxiliary battery has sufficient voltage. For safety, the unit will not close if either terminal voltage is below 2 V (12V), 4 V (24V), or 8 V (48V), preventing unexpected operation during installation or maintenance.

Emergency Parallel Start Feature

A built-in push-button or remote switch input allows manual parallel connection for 30 seconds, providing an emergency start assist if the starter battery is flat. This feature is invaluable for marine, RV, and off-road applications where a failed start could leave you stranded.

Key Features

• 400 A continuous / 2000 A peak current rating for high-demand loads
• Intelligent trend-based switching prevents nuisance disconnects and ensures reliable charging
• Auto-ranging 12/24V detection simplifies installation and reduces setup errors
• Virtually zero voltage drop compared to diode isolators, maximising charge efficiency
• Bidirectional voltage sensing and dual power supply for robust operation
• Emergency start assist via push-button or remote switch for peace of mind
• Microswitch output for remote status monitoring
• Compact, vibration-resistant design with durable metal mounting bracket

Built for Demanding Environments

Encased in a rugged housing with high-current copper terminals, the Cyrix-i is engineered for the harsh conditions of engine rooms, vehicle chassis, and marine installations. The bicolour LED provides at-a-glance status indication, while the microswitch terminals enable integration with remote monitoring systems. Weighing just 0.9 kg, it adds minimal weight while delivering industrial-grade reliability.

Applications

Ideal for dual-battery systems in 4WDs, caravans, motorhomes, boats, and commercial vehicles. Use it to combine a starter battery with an auxiliary deep-cycle battery, or to link multiple battery banks for charging from a single alternator or charger. The Cyrix-i is also suitable for 24V systems in trucks, buses, and heavy equipment.

Upgrade Your Battery Management Today

Replace unreliable diode isolators or basic VSRs with the Victron Cyrix-i Intelligent Battery Combiner and experience smarter, more efficient parallel charging. Order now to ensure your dual-battery system delivers dependable power when you need it most.

Specifications