Description
xVictron Cyrix-ct 12/24V 120A Battery Combiner Kit
The Victron Cyrix-ct is a microprocessor-controlled battery combiner designed for 12V and 24V dual-battery systems. It automatically connects batteries in parallel when one is being charged, and disconnects them when charging stops, protecting the secondary battery from discharge. Suited to marine, motorhome, vehicle and off-grid installations where a starter battery must be kept isolated from a service or leisure battery.
Key Features
- Microprocessor-controlled relay combines batteries when charge voltage is detected, and separates them when it drops, preventing unwanted discharge of the starter battery.
- Rated at 120A continuous current, suitable for high-demand dual-battery setups at 12V or 24V.
- Automatic voltage detection: compatible with both 12V and 24V systems without manual configuration.
- Ignition input terminal allows the combiner to be activated directly when the engine is running, giving additional control over when batteries are joined.
- Retail kit format includes the Cyrix-ct unit and all necessary hardware for a complete installation.
- Compact and solid-state relay design with no moving parts subject to wear, reducing long-term maintenance requirements.
Product Overview
The Cyrix-ct works by monitoring the voltage across the battery banks. When the alternator or charger raises the voltage above the combine threshold (indicating active charging), the unit closes its internal relay and connects the two battery banks in parallel. Both banks then charge simultaneously. When the voltage falls below the disconnect threshold, the relay opens and the banks are isolated again. This prevents a deeply discharged service battery from pulling down a starter battery.
The "ct" designation refers to the ignition input feature. Connecting the ignition terminal to a switched 12V or 24V supply means the Cyrix-ct will also combine the batteries whenever the engine is running, regardless of alternator output voltage. This is particularly useful in vehicles where the alternator voltage rise is slow or where split-charge behaviour needs to be predictable from engine start. The microprocessor logic includes time delays to prevent nuisance switching during voltage fluctuations.
At 120A, the unit handles the current demands of most leisure vehicle and small marine installations. It is not a diode-based isolator, so there is no voltage drop across the combiner when it is closed, meaning both batteries receive the full charge voltage from the alternator or charger.
Specifications
- SKU: CYR010120110R
- System voltage: 12V and 24V (automatic detection)
- Continuous current rating: 120A
- Ignition input: Yes (ct variant)
- Format: Retail kit
- Weight: 0.9 kg
- GTIN: 8719076022169
Applications
- Motorhomes and campervans with a starter battery and separate leisure battery bank.
- Marine vessels requiring isolation between engine start battery and domestic battery bank.
- Commercial vehicles with auxiliary power requirements (refrigeration, tail lifts, lighting).
- Off-grid vehicles and expedition builds where battery management must be automatic and reliable.
- Any dual-battery 12V or 24V installation where diode-based isolators are unsuitable due to voltage drop.
What Is Included
- Victron Cyrix-ct 12/24V 120A battery combiner unit
- Mounting hardware and installation accessories (retail kit)
Installation Notes
Installation should be carried out by a qualified auto-electrician or marine electrician familiar with dual-battery systems. Correct cable sizing and fusing at each battery terminal is essential given the 120A rating. The ignition input wire must be connected to a switched live that is only active when the engine is running. Ensure the unit is mounted in a dry, ventilated location away from fuel lines and direct heat sources. For marine installations, follow BMEA or equivalent wiring standards.
Return Policy
xWe offer a 14-day, no-quibble returns or replacement policy because we want you to be totally satisfied with your purchase.
If you are unhappy in any way with your purchase, you can return it for a refund or a replacement, as long as you return it in the same condition as it arrived (original/undamaged packaging and product) and within 30 days of receiving it. We will pay for your return postage on a faulty item as long as you send it using Royal Mail 2nd class recorded delivery (for EU or International Shipments, you have to use our UPS account, we will provide you with a return label)
Please keep in mind the following:
- Items returned within 14 days but not in their original and undamaged packaging will also incur a -15% charge per package.
- If you return an item that doesn't adhere to our returns procedure or doesn't include a returns form, you may be liable for a £10 administration fee
- Individual items from a bundle can't be returned, refunded or exchanged. If you want a refund/credit/exchange for a bundle, all items must be returned to us.
Before you return your item, please make sure that:
- You follow our returns process (outlined below)
- The goods and packaging are undamaged
IMPORTANT: We need to be able to identify an item with your order. We can only do this if you follow our returns process. Please do not send us items back that do not follow this process as they cannot be identified properly and will not be replaced or refunded.
What delivery method do I need to use when returning an item?
You must send the goods back to us via Royal Mail 2nd class recorded delivery. Refunds on faulty items returned are reimbursed within 5 working days.
Can I return just one item from multiple purchases?
Yes. Once you start the returns process you will go to a page that will allow you to choose which items you want to be replaced or refunded.
Returning faulty goods
If your item is faulty, you need to follow the returns policy, where you will be able to state that it’s faulty. The product will then arrive at our warehouse for testing.
If your purchase is not within 14 days
You can still exchange your item for a different product or for credit to use on the Voltacon Solar or Ledison-led-lights.co.uk websites (-15% from the credit amount).
Returns outside of the 14-day period do not qualify for the free returns policy.
Returning an item within the warranty
If you have a warranty and want to return a faulty item, you just need to follow our standard returns process. When we receive your item, we will then check that it’s within warranty and for any faults before arranging a replacement.