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

The Victron Cyrix-i is a microprocessor-controlled battery combiner designed to connect two battery banks in parallel when both are being charged, and to separate them when charging stops. It is suited to marine, vehicle, and off-grid installations where a starter battery and a service battery must be kept isolated under load but charged simultaneously from a single source.

Key Features

• Rated at 400A continuous current, suitable for high-demand 12V and 24V systems.
• Microprocessor-controlled switching logic monitors battery voltage and connects banks only when a charge source is detected, preventing the starter battery from being drained by service loads.
• Automatic operation with no manual intervention required once installed.
• Compatible with lead-acid battery chemistries including AGM, gel and flooded types.
• Compact and robust construction with a weight of 0.9 kg, suitable for installation in confined spaces.
• Operates across both 12V and 24V systems without reconfiguration.
• Voltage-sensing logic prevents premature connection during engine cranking, protecting the service bank from voltage dips.

Product Overview

The Cyrix-i works by continuously monitoring the voltage of both battery banks. When the voltage on either bank rises above a set threshold (indicating a charge source such as an alternator or shore power charger is active), the unit connects the two banks in parallel so both charge simultaneously. When the voltage drops back below the threshold, the banks are separated, ensuring the starter battery retains enough charge for engine starting regardless of how deeply the service bank has been discharged.

Unlike a simple relay or diode-based isolator, the Cyrix-i uses microprocessor logic to apply time delays and hysteresis to its switching decisions. This prevents rapid cycling caused by voltage fluctuations and avoids connecting a discharged bank to a healthy one at the wrong moment. The 400A rating means it can handle the full output of most vehicle alternators and battery chargers without becoming a bottleneck in the charging circuit.

The unit is designed to be wired directly between the positive terminals of the two battery banks. It requires no external control signal and draws negligible standby current, making it well suited to installations where the system may sit unused for extended periods.

Specifications

• SKU: CYR010400000
• Voltage compatibility: 12V and 24V
• Continuous current rating: 400A
• Weight: 0.9 kg
• GTIN: 8719076022251

Applications

• Marine vessels with separate starter and service battery banks charged from a single alternator.
• Motorhomes and campervans requiring isolation between the vehicle starter battery and the leisure battery bank.
• Commercial vehicles with auxiliary power systems that must not compromise engine starting reliability.
• Off-grid cabins or static installations where two battery banks are charged from a single charger or solar system.
• Agricultural and plant machinery with high-current dual-battery configurations.

What Is Included

• 1 x Victron Cyrix-i 12/24V 400A intelligent battery combiner

Installation Notes

The Cyrix-i should be installed by a qualified electrician or marine electrical engineer familiar with high-current DC systems. Connections must be made with appropriately rated cable and correctly sized fusing on each battery bank. Ensure both battery banks share a common negative before installation. The unit is not suitable for use with lithium battery chemistries unless the lithium battery management system is confirmed compatible with voltage-based combiners.