{"product_id":"victron-cyrix-li-ct-12-24v-120a-battery-combiner-bms-control","title":"Victron Cyrix-Li-ct 12\/24V-120A intelligent Li-ion battery combiner","description":"\u003cp\u003eThe Victron Energy Cyrix-Li-ct 120A is a microprocessor-controlled intelligent battery combiner purpose-built for systems combining a lead-acid starter battery with a Victron LiFePO4 service battery. Available in 12\/24V and 24\/48V variants, it automatically connects the two battery banks in parallel to allow the alternator or shore charger to charge both batteries simultaneously — then disconnects them immediately when the VE.Bus BMS signals a cell overvoltage or overtemperature alarm, protecting the lithium cells from damage caused by uncontrolled charge current.\u003c\/p\u003e\n\u003cp\u003eUnlike conventional voltage-sensitive relays that connect and disconnect based solely on battery terminal voltage, the Cyrix-Li-ct adds a BMS control input that makes its engage and disengage logic lithium-aware. The relay will only engage when the VE.Bus BMS Charge Disconnect output is high — indicating that charging is permitted — and one of its power terminals senses 13.4V or more (26.8V for 24V systems). When the BMS signals a cell overvoltage or overtemperature event by pulling the Charge Disconnect output free floating, the Cyrix-Li-ct disengages immediately — protecting the lithium cells rather than waiting for the standard voltage-based disconnect threshold.\u003c\/p\u003e\n\u003cp\u003eA built-in transient voltage suppressor limits the voltage spike that can occur when the Cyrix-Li-ct suddenly disengages under load — an important protection feature in systems where the alternator field collapses rapidly when the combiner opens. An emergency start assist function is also included: a short negative pulse on the start assist terminal closes the relay for 30 seconds, allowing the lead-acid starter battery to be boosted from the LiFePO4 service battery in an emergency without any permanent parallel connection.\u003c\/p\u003e\n\u003cp\u003eWith a maximum continuous and breaking current of 120A at 12V or 24V, a current consumption when open of less than 4mA, and an IP54-rated enclosure measuring just 46 x 46 x 80mm and weighing 110g, the Cyrix-Li-ct is a compact, low-power solution for alternator charge management in marine, RV, and vehicle lithium battery systems. Certified to automotive ECE R10-6 and EN\/IEC 60335-1 safety standards.\u003c\/p\u003e\n\u003cp\u003e\u003ciframe title=\"YouTube video player\" src=\"https:\/\/www.youtube.com\/embed\/dzU_pQFa19s?si=N3FiNhxuCPhLarJx\"\u003e\u003c\/iframe\u003e\u003c\/p\u003e\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003ch4\u003eLithium-Aware BMS Control Input\u003c\/h4\u003e\n\u003cp\u003eThe Cyrix-Li-ct only engages when the VE.Bus BMS Charge Disconnect output is high — confirming that charging is safe for the lithium cells. When the BMS signals a cell overvoltage or overtemperature event by pulling the output free floating, the Cyrix-Li-ct disengages immediately, protecting the LiFePO4 cells from uncontrolled alternator charge current without delay.\u003c\/p\u003e\n\u003ch4\u003eVoltage-Based Engage Logic with Intelligent Delay\u003c\/h4\u003e\n\u003cp\u003eThe relay engages when one of its power terminals senses 13.4V or more (26.8V for 24V systems), with a time delay that reduces progressively as voltage increases — from 120 seconds at moderate charge voltage, to 30 seconds at higher voltage, to 4 seconds above 13.9V. This prevents nuisance engagement during brief voltage transients while responding quickly at sustained alternator output voltage.\u003c\/p\u003e\n\u003ch4\u003eImmediate Disengage on Alarm or Low Voltage\u003c\/h4\u003e\n\u003cp\u003eThe Cyrix-Li-ct disengages immediately when either the BMS Charge Disconnect output goes free floating or battery voltage drops below 13.2V (26.4V for 24V systems), with a secondary 10-second delayed disconnect between 13.2V and 13.3V. This prevents the lead-acid starter battery from discharging the lithium service battery under low-load conditions.\u003c\/p\u003e\n\u003ch4\u003eBuilt-In Transient Voltage Suppressor\u003c\/h4\u003e\n\u003cp\u003eA built-in transient voltage suppressor clamps the voltage spike that occurs when the relay suddenly disengages under alternator load — protecting connected electronics, the alternator, and the lithium battery BMS from voltage transients that can exceed safe levels when a high-current relay opens abruptly in an inductive circuit.\u003c\/p\u003e\n\u003ch4\u003eEmergency Start Assist Function\u003c\/h4\u003e\n\u003cp\u003eA short negative pulse on the start assist terminal forces the relay closed for 30 seconds, allowing the LiFePO4 service battery to boost a depleted lead-acid starter battery in an emergency — without any permanent parallel connection between the two banks and without overriding the normal BMS protection logic during regular operation.\u003c\/p\u003e\n\u003ch4\u003eUltra-Low Standby Current — Under 4mA\u003c\/h4\u003e\n\u003cp\u003eWith a current consumption of less than 4mA when open, the Cyrix-Li-ct draws negligible standby power from the battery bank during periods when the relay is disengaged — making it suitable for permanent installation in systems where minimising parasitic drain during extended lay-up or storage is important.\u003c\/p\u003e\n\u003ch4\u003eCompact IP54-Rated Enclosure\u003c\/h4\u003e\n\u003cp\u003eThe IP54-rated enclosure — measuring just 46 x 46 x 80mm and weighing only 110g — is dust-protected and splash-resistant, making the Cyrix-Li-ct suitable for installation in exposed locations in engine bays, bilges, and vehicle battery compartments without requiring an additional enclosure or protection cover.\u003c\/p\u003e\n\u003ch4\u003e12\/24V and 24\/48V Variants Available\u003c\/h4\u003e\n\u003cp\u003eAvailable in two voltage variants — 12\/24V-120A (CYR010120412) for 12V and 24V lithium systems, and 24\/48V-120A for 24V and 48V systems — the Cyrix-Li-ct covers the most common vehicle and marine dual-voltage system configurations with a single compact and proven relay design.\u003c\/p\u003e\n\u003ch5\u003eSpecifications\u003c\/h5\u003e\n\u003ctable class=\"product-spec-table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eVoltage Variants\u003c\/td\u003e\n\u003ctd\u003e12\/24V-120A (CYR010120412) | 24\/48V-120A\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eContinuous and Breaking Current (12V or 24V)\u003c\/td\u003e\n\u003ctd\u003e120A\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBreaking Capacity (48V)\u003c\/td\u003e\n\u003ctd\u003e40A (24\/48V variant only)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eConnect Voltage (12V \/ 24V system)\u003c\/td\u003e\n\u003ctd\u003e13.4V \/ 26.8V (with BMS Charge Disconnect input high)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDisconnect Voltage (12V \/ 24V system)\u003c\/td\u003e\n\u003ctd\u003eImmediate below 13.2V \/ 26.4V | 10s between 13.2-13.3V \/ 26.4-26.6V\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eControl Input\u003c\/td\u003e\n\u003ctd\u003eEngages: high (~battery voltage) | Disengages: free floating or pulled low\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCurrent Consumption (open)\u003c\/td\u003e\n\u003ctd\u003e\u0026lt;4mA\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eProtection Class\u003c\/td\u003e\n\u003ctd\u003eIP54\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWeight\u003c\/td\u003e\n\u003ctd\u003e0.11 kg (0.24 lbs)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDimensions (H x W x D)\u003c\/td\u003e\n\u003ctd\u003e46 x 46 x 80 mm (1.8 x 1.8 x 3.2 inch)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch5\u003eDatasheets\u003c\/h5\u003e\n\u003cp\u003e\u003ca href=\"https:\/\/www.victronenergy.com\/upload\/documents\/Datasheet-Cyrix-Li-ion-120-A-EN.pdf\" target=\"_blank\"\u003eDatasheet\u003c\/a\u003e\u003c\/p\u003e","brand":"Victron Energy","offers":[{"title":"Default Title","offer_id":47131389886713,"sku":"CBV20112","price":75.65,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0783\/8538\/1625\/files\/Product-CBV20112-1.webp?v=1778863099","url":"https:\/\/emarineinc.com\/products\/victron-cyrix-li-ct-12-24v-120a-battery-combiner-bms-control","provider":"eMarine","version":"1.0","type":"link"}