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Victron Cyrix-Li-ct Intelligent Li-ion Battery Combiner 12/24V-120A

120A BMS-Controlled Combiner with Start Assist - 46x46x80mm IP54


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DESCRIPTION

Victron Cyrix-Li-ct: Intelligent Battery Combiner for LiFePO4 and Lead Acid Systems

Seamless Parallel Connection Between Starter and Lithium Batteries

The Victron Cyrix-Li-ct 12/24V-120A is a microprocessor-controlled battery combiner engineered to parallel a lead acid starter battery with a LiFePO4 (lithium iron phosphate) service battery. It integrates directly with the Victron VE.Bus BMS, providing a critical layer of protection against cell undervoltage, overvoltage, and overtemperature events. This ensures your lithium battery bank remains within safe operating limits while maintaining the starter battery's charge.

Unlike generic voltage sensing relays (VSRs), the Cyrix-Li-ct responds to BMS control signals rather than voltage alone. This prevents premature disconnection or unintended cycling, a common issue with standard combiners in lithium systems. The result is a more stable, reliable dual-battery setup for caravans, motorhomes, marine vessels, and off-grid installations.

How the Cyrix-Li-ct Protects Your Lithium Investment

Lithium batteries require precise charge and discharge management. The Cyrix-Li-ct acts as a gatekeeper, engaging only when the BMS confirms safe conditions. It disengages instantly if the BMS signals a fault, such as cell overvoltage or high temperature, isolating the lithium battery from the alternator or charger. This rapid response helps prevent irreversible cell damage and extends battery service life.

Key protective functions include:

  • BMS-controlled engagement: The relay closes only when the VE.Bus BMS Charge Disconnect output is high, ensuring charging only occurs under safe conditions.
  • Immediate disengagement: If the BMS control input becomes free floating (indicating a fault), the Cyrix opens without delay, halting current flow.
  • Undervoltage lockout: The relay disengages when battery voltage drops below 13.2V (12V system) or 26.4V (24V system), preventing deep discharge of the starter battery.
  • Transient voltage suppression: A built-in suppressor limits voltage spikes during sudden disconnection, protecting sensitive electronics.

Start Assist: Emergency Power When You Need It

A standout feature is the start assist function. A short negative pulse on the control input closes the relay for 30 seconds, allowing the lithium service battery to assist a depleted starter battery. This can be a lifesaver in remote locations, providing a temporary boost without manual jump leads. The function is easily activated via a momentary switch connected to the BMS interface.

Engineered for Demanding Environments

The Cyrix-Li-ct is built to withstand the rigours of mobile and marine applications. Its compact, lightweight design (46 x 46 x 80 mm, 0.11 kg) simplifies installation in tight spaces. The IP54 protection rating guards against dust ingress and water splashes, while the robust 3/8"-16 (Approx. M10) stud terminals accommodate heavy-duty lugs up to 4/0 AWG (approx. 95 mm²), ensuring low-resistance connections for 120 A continuous current.

An integrated LED provides clear visual feedback on system status, aiding diagnostics and troubleshooting. The front-facing wiring diagram and technical reference further streamline setup, reducing installation time and potential errors.

Typical Applications

  • Caravans and motorhomes: Automatically charge the house lithium battery from the alternator while protecting the starter battery.
  • Marine systems: Combine a lead acid engine battery with a LiFePO4 house bank, with BMS-coordinated safety.
  • Off-grid solar: Integrate with Victron inverter/chargers and MPPT controllers for a fully managed energy system.
  • Commercial vehicles: Maintain auxiliary lithium batteries for lifts, refrigeration, or onboard equipment.

Installation and Compatibility Notes

The Cyrix-Li-ct requires a Victron VE.Bus BMS for operation; it is not a standalone voltage sensing relay. For systems without a VE.Bus BMS, consider the Victron Cyrix-ct or BatteryProtect range. Always refer to the Victron wiring guidelines and ensure cable sizing matches the 120 A rating. Note typical de-rating factors apply for continuous high-current use in elevated temperatures.

Take Control of Your Dual-Battery System

Upgrade your energy management with the Victron Cyrix-Li-ct 12/24V-120A. Designed for seamless integration with Victron lithium batteries and BMS, it delivers the precision and protection your system demands. Order today to ensure reliable, automated battery combining on your next adventure.


SKU: Vic-CYR010120412

SPECIFICATIONS

Specifications

Part NumberCYR010120412
DescriptionIntelligent Li-ion Battery Combiner
ModelCyrix-Li-ct 12/24-120
Battery CombinationLead acid starter battery and a LiFePO4 battery
Continuous Current And Breaking Capacity At 12 V Or 24 V120 A
Breaking Capacity At 48 Vn. a.
Control InputThe Cyrix engages when the control input is high (appr. battery voltage); The Cyrix disengages when the control input is left free floating or pulled low
Connect Voltage (12 V System)13.4 V < V < 13.7 V: 120 s; 13.7 V < V < 13.9 V: 30 s; V > 13.9 V: 4 s
Connect Voltage (24 V System)26.8 V < V < 27.4 V: 120 s; 27.4 V < V < 27.8 V: 30 s; V > 27.8 V: 4 s
Disconnect ConditionWhen its control output becomes free floating, signalling cell over voltage or cell over temperature, and/or when battery voltage drops below 13.2 V
Current Consumption When Open<4 mA
Protection CategoryIP54
Weight0.11 kg (0.24 lbs)
Dimensions H x W x D46 x 46 x 80 mm (1.8 x 1.8 x 3.2)
Start Assist FunctionA short negative pulse will close the relay during 30 seconds

SKU: Vic-CYR010120412
Barcode: 8719076034339
Model #: CYR010120412
MPN: CYR010120412

WARRANTY

Victron Energy Limited Warranty Policy

Victron Energy warrants its products to be free from defects in workmanship and materials for a period of 5 years from the date of purchase by the end user, with a maximum of 66 months from the Victron Energy invoice date. Exceptions on this are: lead acid batteries; 2 years from date of purchase by the end user, with a maximum of 30 months from the Victron Energy invoice date, Lithium-ion batteries; 3 years from date of purchase by the end user. In addition to this proof of correct battery usage is required when making a battery warranty claim.

During this period, Victron Energy will, at its option, repair or replace the defective product free of charge. The warranty does not include performing or reimbursing de‐installation, transportation and re‐installation. This warranty will be considered void if the unit has suffered any physical damage or alteration, either internally or externally, and does not cover damages arising from improper use like: • Reverse of battery polarity. • Inadequate connection. • Mechanical shock or deformation. • Contact with liquid or oxidation by condensation. • Use in inappropriate environment (dust, corrosive vapor, humidity, high temperature, biological infestation...). • Breakage or damage due to lightning. • Connection terminals and screws destroyed or other damages, like overheat, due to insufficient tightening. • For any electronical breakage except due to lightning (reverse polarity, over‐voltage due to external cause), the state ofthe internal control diode and of the inputs/output X and Y capacitors determine the warranty.

This warranty will not apply where the product has been misused, neglected, improperly installed, or repaired by anyone else than Victron Energy or one of its authorized Qualified Service Partners. In order to qualify for the warranty, the product must not be disassembled or modified.

Repair or replacement are our sole remedies and Victron Energy shall not be liable for damages, whether direct, incidental,special, or consequential, even caused by negligence or fault.

Victron Energy owns all parts removed from repaired products. Victron Energy uses new or reconditioned parts made by various manufacturers in performing warranty repairs and building replacement products. If Victron Energy repairs or replaces a part of a product, its warranty term is not extended. In case of replacement the new component has a warranty of 6 months, without effect on the initial warranty period. All remedies and the measure for damages are limited to the above. Victron Energy shall in no event be liable for consequential, incidental, contingent orspecial damages, even if having been advised of the probability of such damages. Any and all other warranties expressed or implied arising by law, course of dealing, course of performance, usage of trade or otherwise, including but not limited to implied warranties of merchantability and fitness for a particular purpose, are limited in duration to a period of two (2) years from the date of purchase.

Life Support Policy As a general policy, Victron Energy, does not recommend the use of any of its products in life support applications where failure or malfunction of the Victron Energy's product can be reasonably expected to cause failure of the life support device or to significantly affect its safety or effectiveness. Victron Energy does not recommend the use of any of its products in direct patient care. Victron Energy will not knowingly sell its products for use in such applications unless it receives in writing assurances satisfactory to Victron Energy that the risks of injury or damage have been minimized, the customer assumes all such risks, and the Liability of Victron Energy is adequately protected under the circumstances.

As a product requires service, it must be brought back to the place of purchase. In case no contact can be taken with the merchant, or if he is either unable or not allowed to provide service, direct contact should be taken with Victron Energy.

Warranty on Repairs The warranty period on products or on printed circuits boards repaired by Victron Energy as well as on printed circuit boards for replacement is 6 months from delivery by Victron Energy.

Transport It is the responsibility of the sender to sufficiently package these products. The transport must be organized in a way to avoid any damage, especially when a single unit or heavy unit is sent.

Severability If a part of the terms and conditions set out above is held invalid, void or unenforceable due to any particular national or international legislation, it shall not affect other parts of the terms and conditions remaining.

For Australia only Our goods come with guarantees that cannot be excluded under the Australian Consumer Law. You are entitled to a replacement or refund for a major failure and compensation for any other reasonably foreseeable loss or damage. You are also entitled to have the goods repaired or replaced if the goods fail to be of acceptable quality and the failure does not amount to a major failure.

Exotronic provides high-quality products and solutions tailored for B2B and commercial customers, including commercial businesses, caravan manufacturers, marine electricians, OEMs, as well as emergency services, and more.

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