Victron Cyrix dual battery combiner:
Some battery combiners (also called voltage controlled relay, or split charge relay) will disconnect a battery in case of a short but high amperage load. A battery combiner also may fail to connect a large but discharged battery bank because the DC voltage immediately drops below the disengage value once the batteries are connected. The software of the Cyrix-ct 12/24 does more than simply connect and disconnect based on battery voltage and with a fixed time delay. The Cyrix-ct 12/24 looks at the general trend (voltage increasing or decreasing) and reverses a previous action only if the trend has reversed during a certain period of time. The time delay depends on the voltage deviation from the trend. (for Battery Combiners with multiple engage/disengage profiles, please see the Cyrix-i 400)
Long bolts to allow connection of more than one power cable- Cyrix 12/24-120: 13 mm (M6)Cyrix 12/24-230: 16 mm (M8)
Protection against overheating (due to a long duration overload e.g.)- The Cyrix will disengage in case of excessive contact temperature, and reengage again after it has cooled down.
LED status indication (Cyrix 12/24 230 only)-
LED on: engagedLED 10 s flash: disengaged
LED 2 s flash: connectingLED 2 s blink: disconnecting
LED 0,25 s blink: alarm (over temperature; voltage > 16 V; both batteries < 10 V; one battery < 2 V) (multiply by two for 24 V)
12/24 V auto ranging- The Cyrix-ct 12/24 automatically detects system voltage.
No voltage loss- Cyrix battery combiners are an excellent replacement for diode isolators. The main feature is that there is virtually no voltage loss so that the output voltage of alternators or battery chargers does not need to be increased.
Prioritising the starter battery- In a typical setup the alternator is directly connected to the starter battery. The accessory battery, and possibly also a bow thruster and other batteries are each connected to the starter battery with Cyrix battery combiners. When a Cyrix senses that the starter battery has reached the connect voltage it will engage, to allow for parallel charging of the other batteries.
Bidirectional voltage sensing and power supply from both batteries- The Cyrix senses the voltage of both connected batteries. It will therefore also engage if for example the accessory battery is being charged by a battery charger. The Cyrix-ct 12/24 has a dual power supply. It will therefore also close if the voltage on one battery is too low to operate the Cyrix. In order to prevent unexpected operation during installation or when one battery has been disconnected, the Cyrix-ct 12/24 will not close if the voltage on one of the two battery connections is lower than 2 V (12 V battery) or 4 V (24 V battery).
Parallel connection in case of emergency (Start Assist)- The Cyrix can also be engaged with a push button (Cyrix remains engaged during 30 seconds) or a switch to connect batteries in parallel manually. This is especially useful in case of emergency when the starter battery is discharged or damaged.
Cyrix Battery Combiner
LED status indication
Cranking rating (5 seconds)
From 13 V to 13,8 V and 26 to 27,6 V
with intelligent trend detection
From 11 V to 12,8 V and 22 to 25,7 V
with intelligent trend detection
Current consumption when open
Current consumption when closed
12 V : 220 mA 24 V : 120 mA
12 V : 320 mA 24 V : 180 mA
Yes (Cyrix remains engaged during 30 seconds)
Control cable included (length 1 m)
Weight kg (lbs)
Dimensions h x w x d in mm
(h x w x d in inches)
46 x 46 x 80
(1.8 x 1.8 x 3.2)
65 x 100 x 50
(2.6 x 4.0 x 2.0)