Victron Cyrix-Li-charge 12/24V-230A Intelligent Charge Relay (CYR010230430)

The Cyrix-Li-charge 12/24V-230A is a microprocessor-controlled charge relay designed to combine a lithium (LiFePO4) service battery with a starter battery in 12V or 24V systems. It allows the alternator or charger to charge both batteries simultaneously, while protecting the lithium battery from unsafe charging conditions. Suitable for marine, vehicle and off-grid installations where a lithium service bank is paired with a conventional lead-acid starter battery.

Key Features

• Rated at 230A continuous current, suitable for high-demand dual-battery systems in 12V or 24V configurations.
• Microprocessor-controlled operation monitors voltage on both battery banks and connects them only when charging conditions are safe and appropriate.
• Specifically designed for lithium battery systems: the relay opens immediately if the Battery Management System (BMS) signals a charge disconnect, preventing overcharge of the lithium bank.
• Responds to a BMS charge-disconnect signal within milliseconds, protecting cell integrity and prolonging battery life.
• Automatically disconnects when charging ceases, preventing the starter battery from being drained by the lithium service bank.
• Compatible with 12V and 24V systems without any manual configuration required.
• Compact and lightweight at 0.3 kg, with a straightforward wiring installation.

Product Overview

The Cyrix-Li-charge relay sits between a lithium service battery and a lead-acid starter battery. When the alternator or an external charger raises the voltage on the starter battery side above the connection threshold, the relay closes and allows charge current to flow into the lithium bank as well. When charging stops and voltage drops, the relay opens again, keeping the two banks isolated. This prevents the lithium battery from back-feeding the starter battery and ensures the engine always has a reliable start.

The critical difference between this unit and a standard Cyrix-ct relay is its direct integration with a lithium BMS. The BMS charge-disconnect output connects directly to the Cyrix-Li-charge. If the BMS detects a cell overvoltage or temperature condition and signals a charge stop, the relay opens within milliseconds regardless of the voltage present on the bus. This is a hard requirement for safe lithium operation that a conventional voltage-sensing relay cannot provide. Installers working with lithium battery systems should treat this BMS interface as a mandatory part of the installation, not an optional feature.

At 230A, the relay handles the full output of most marine and vehicle alternators without derating. The unit auto-detects 12V or 24V system voltage, so no jumper or DIP switch configuration is needed on installation.

Technical Specifications

Applications

• Marine vessels with a lithium service bank and a separate lead-acid engine start battery, charged via alternator.
• Motorhomes and campervans with a lithium leisure battery and a vehicle starter battery.
• Off-grid vehicles and expedition builds where alternator charging feeds a lithium house bank.
• Any 12V or 24V dual-battery system requiring safe, automatic charge sharing between lithium and lead-acid banks.

What Is Included

• 1x Victron Cyrix-Li-charge 12/24V-230A intelligent charge relay

Installation Notes

Installation should be carried out by a qualified electrician or experienced marine/vehicle electrical installer. The BMS charge-disconnect output must be wired to the Cyrix-Li-charge control input for the unit to function correctly and safely with a lithium battery. Omitting this connection removes the primary protection mechanism for the lithium cells. Ensure all cabling is rated for the full 230A continuous load and that appropriate fusing is fitted on both battery connections in accordance with the wiring regulations applicable to your installation (BS 8491 for marine, or equivalent). Refer to the Victron Energy installation manual for full wiring diagrams and connection details before commencing work.