Victron Energy Cyrix Li-ion 120A Battery Combiner

Overview

The Victron Energy Cyrix Li-ion 120 A Series is a group of BMS-controllable relays for Victron LiFePO4 battery systems, with versions for charge control, load control, and battery combining in 12/24V or 24/48V installations.

Each unit in this range is rated at 120 A for continuous current and breaking capacity at 12 V or 24 V. The charge and load versions for 24/48V systems also support 48 V use with a 40 A breaking capacity at 48 V. The housing is IP54 rated, measures 46 x 46 x 80 mm, and weighs about 0.11 kg, which makes it practical for battery lockers, DC panels, and protected equipment spaces on board.

These relays are used where a Victron VE.Bus BMS needs to control equipment that cannot be switched directly by the BMS. In a marine lithium installation, that can mean disconnecting loads during a low-cell condition, stopping charge sources during cell over-voltage or temperature events, or combining a lead-acid starter battery with a LiFePO4 service bank when charging conditions are safe.

Key features

• 120 A current rating at 12 V or 24 V across the series for battery combining, charger control, or load control duties.
• 12/24V and 24/48V variants cover common low-voltage DC systems used on cruising boats, workboats, and larger onboard power installations.
• VE.Bus BMS control input lets the relay engage when the BMS allows operation and disengage when the control input is free floating or pulled low.
• Cyrix-Li-charge versions connect a battery charger after a short delay when the BMS charge disconnect signal is high and the required battery voltage is present.
• Cyrix-Li-load versions disconnect DC loads when the BMS load control signal is no longer present, helping protect a LiFePO4 bank from deep discharge.
• Cyrix-Li-ct version can parallel-connect a lead-acid starter battery and a LiFePO4 battery, and includes a start assist function that closes the relay for 30 seconds.
• IP54 protection category, 46 x 46 x 80 mm dimensions, 0.11 kg weight, and current draw under 4 mA when open support clean installation in protected onboard electrical spaces.

Variants

The Victron Energy Cyrix Li-ion 120 A Series is offered in five configurations. The main differences are the relay function and the voltage range.

All variants belong to the 120 A Cyrix Li-ion range and share the same housing dimensions, IP54 protection category, and low open-state current draw. The charge and load versions are available for both 12/24V and 24/48V systems, while the Cyrix-Li-ct version in this selection is a 12/24V battery combiner.

• CYR010120412, Series Model Cyrix-Li-ct, Voltage Range 12/24V. This version is for combining a lead-acid starter battery with a LiFePO4 battery under VE.Bus BMS control, with start assist available for engine starting support.
• CYR010120430, Series Model Cyrix-Li-charge, Voltage Range 12/24V. This version controls a battery charger in 12 V or 24 V lithium systems and disconnects charging when the BMS signals a charge stop condition.
• CYR010120450, Series Model Cyrix-Li-load, Voltage Range 12/24V. This version controls DC loads in 12 V or 24 V lithium systems where the BMS needs to remove loads during a low-cell condition.
• CYR020120430, Series Model Cyrix-Li-charge, Voltage Range 24/48V. This version brings the charger-control function to 24 V and 48 V battery systems, with a 40 A breaking capacity at 48 V.
• CYR020120450, Series Model Cyrix-Li-load, Voltage Range 24/48V. This version brings the load-control function to 24 V and 48 V battery systems, with a 40 A breaking capacity at 48 V.

Installation and setup

Install the relay close to the battery system or DC distribution equipment so cable runs stay short and voltage drop can be managed. The IP54 enclosure is suitable for protected marine electrical areas where dust or incidental spray may be present, but it should still be kept out of direct deck wash, bilge water, and standing moisture.

The control wiring should follow the intended function of the selected model. Charge versions connect to the BMS charge disconnect signal, load versions connect to the BMS load disconnect signal, and the Cyrix-Li-ct version is used where the starter and lithium banks need controlled paralleling. Cable size, fusing, and terminal protection should be selected for the actual DC system current and the standards used on the vessel.

Compatibility and use on board

This series fits boats using Victron LiFePO4 batteries with a VE.Bus BMS, especially where existing chargers, inverter/chargers, alternator-linked starter circuits, or DC loads need controlled switching rather than direct BMS control. It is a practical match for lithium refits, offshore cruising systems, fishing boats with high DC loads, and service banks where controlled charge and load behavior matters.

The selected voltage range must match the vessel battery architecture. Use 12/24V versions for 12 V or 24 V systems, and 24/48V charge or load versions for 24 V or 48 V systems.