Victron Cyrix-CT / Cyrix-Li-CT

Victron Cyrix-CT and Li-CT - are dual battery relays for modern boat battery systems! The batteries are connected in parallel when the terminal voltage of the starter battery reaches a preset level. In the same way, the batteries are disconnected from each other when the terminal voltage drops below the float voltage level. An excellent alternative to traditional DC-DC chargers, such as the Victron Orion 12V 12V 18A DC-DC charger. The most important feature is that the voltage loss is practically zero, so there is no need to raise the output voltage of the alternator or battery charger.

Cyrix-CT - is particularly well suited for 12V AGM systems and is an extremely good dual battery relay between the boat's AGM starter battery and, for example, the AGM battery of the bow-mount trolling motor. Also excellent for motorhomes where the leisure battery is a lead-acid or AGM battery.

Victron Cyrix Li-CT - on the other hand, is designed, for example, for use between the boat's AGM starter battery and the LiFePO4 lithium battery of the trolling motor or electronics. It understands that the source battery is an AGM battery and the target battery is a LiFePO4 lithium battery. Also suitable for motorhomes where the leisure battery is a LiFePO4 lithium battery.

• Please note that only LiFePO4 lithium batteries may be installed as the target battery. For example, a Rebelcell Li-Ion battery must not be connected to the system, because the voltage of a Rebelcell Li-Ion battery is lower than that of LiFePO4 lithium batteries.

Also available with a Victron MEGA fuse holder and a 100A MEGA fuse. The Victron Cyrix withstands a momentary current of 125A, so a 100A fuse is a safe choice that prevents the Cyrix from being damaged if a fault occurs.

Victron Cyrix-CT and Cyrix-Li-CT key features:

• Easy to install and connect
• No programming required
• Disconnects automatically when the float voltage level drops below 13.2V
• Cyrix-CT between a lead-acid or AGM starter battery and a second AGM battery.
• Cyrix-Li-CT between a lead-acid or AGM starter battery and a lithium battery
• IP54
  
• Can be used in 12V-12V and 24V-24V systems - The Victron Cyrix does not work in 12V to 24V systems. If your trolling motor battery is 24V, always use a Victron Orion DC-DC charger (Victron Orion 12V 24V 15A)
• Use a 100A - 120A circuit breaker, ANL fuse or strip fuse with both models

Victron Cyrix-Li-CT - The Cyrix-Li-CT will parallel connect a lead-acid starter battery and a LiFePO4 battery:

• if the Charge Disconnect output of the VE.Bus BMS is high, and
• if it senses 13.4V (resp. 26.8V) or more on one of its power terminals.

The Cyrix will disengage immediately:

• when its control output becomes free floating, signalling cell overvoltage or cell over temperature, and/or
• when battery voltage drops below 13.2V.

Start assist function: a short negative pulse will close the relay for 30 seconds.
A built-in transient voltage suppressor will limit the voltage spike that may occur when the Cyrix suddenly disengages due to cell overvoltage or over temperature.

Note! More detailed technical data after the wiring diagrams

Victron Cyrix-CT / Cyrix-Li-CT Main Features: 

• LED status indication: No  
• Continuous current: 120A 
• Cranking rating (5 seconds): 180A 
• Current consumption when open: <4 mA 
• Current consumption when closed: 12 V : 220 mA or 24 V : 120 mA 
• Start Assist: Yes (Cyrix remains engaged during 30 seconds) 
• Protection category: IP54 
• Weight: 0.11 kg (0.24 lbs) 
• Dimensions (h x w x d): 46 x 46 x 80 mm 

• Cyrix-CT Connect (V) / Delay :
  V < 13 V: Remains open
  13.0 V < V < 13.2 V: 10 min
  13.2 V < V < 13.4 V: 5 min
  13.4 V < V < 13.6 V: 1 min
  13.6 V < V < 13.8 V: 4 sec
  
  
• Disconnect (V) / Delay : 
  V < 11 V: 0 sec
  11.0 V < V < 12.0 V: 1 sec
  12.0 V < V < 12.2 V: 10 sec
  12.2 V < V < 12.4 V: 30 sec
  12.4 V < V < 12.8 V: 3 min
  > 12.8 V: remains closed
  > 16 V: over voltage disconnect
   
• Cyrix-Li-CT Connect (V) / Delay :
  13.4V < V < 13.7V: 120 s
  13.7V < V < 13.9V: 30 s
  V > 13.9V: 4 s
  
  
• Disconnect (V) / Delay :
  13.3V < V < 13.2V: 10 s
  V < 13.2V: immediate
  
  
  
  
  
  
   

Product text updated 26.9.2026.