SKU: 59434215843

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

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Description

Victron Cyrix-ct Intelligent Battery Combiner 12/24V-120A VSRVictron Cyrix ct 120A Intelligent Battery Combiner for Dual Battery Systems Advanced Voltage Sensing Relay with Trend Detection for Reliable Parallel Charging The Victron Cyrix ct 12 24V 120A is a microprocessor controlled intelligent battery combiner that functions as a bidirectional voltage sensitive relay (VSR). Unlike conventional split charge relays that rely on simple voltage thresholds and fixed time delays, the Cyrix ct analyses the overall

Victron Cyrix-ct 120A Intelligent Battery Combiner for Dual Battery Systems

Advanced Voltage Sensing Relay with Trend Detection for Reliable Parallel Charging

The Victron Cyrix-ct 12/24V-120A is a microprocessor-controlled intelligent battery combiner that functions as a bidirectional voltage sensitive relay (VSR). Unlike conventional split charge relays that rely on simple voltage thresholds and fixed time delays, the Cyrix-ct analyses the overall voltage trend to prevent nuisance switching. This ensures your auxiliary battery bank charges reliably from the alternator or mains charger without premature disconnection under heavy loads or reconnection when surface charge dissipates.

Engineered for 12V and 24V automotive and marine electrical systems, the Cyrix-ct auto-detects system voltage and provides a continuous current rating of 120 A, making it suitable for charging large domestic battery banks, bow thruster batteries, and other onboard equipment. Its bidirectional sensing allows the combiner to engage when either battery reaches the connect voltage, so charging sources on either side can parallel the banks automatically.

Intelligent Trend Detection Eliminates Unwanted Cycling

Standard voltage-controlled relays often disconnect a battery when a short, high-current load causes a momentary voltage dip, or fail to connect a deeply discharged bank because the voltage collapses below the disconnect threshold immediately after engagement. The Cyrix-ct’s software monitors the rate and direction of voltage change over time, reversing a previous action only if the trend has genuinely reversed. The time delay adapts based on the deviation from the trend, providing stable operation in demanding conditions.

Key Features

  • 120 A continuous current rating with 180 A cranking assist for emergency parallel starts
  • 12/24 V auto-ranging detects system voltage automatically, no manual configuration needed
  • Bidirectional voltage sensing and dual power supply allows engagement from either battery, even if one is deeply discharged
  • Start Assist function via push button or switch provides 30-second emergency parallel connection
  • Over-temperature protection disengages the relay if contact temperature becomes excessive, re-engaging after cooling
  • Virtually zero voltage drop across the contacts, eliminating the need to increase alternator or charger output voltage
  • Prioritises starter battery by connecting auxiliary banks only after the starter reaches the connect voltage
  • Compact IP54-rated housing (46 x 46 x 80 mm) withstands dust and water spray in engine bays and marine compartments
  • Low power consumption: less than 4 mA when open, 220 mA (12 V) or 120 mA (24 V) when closed
  • 13 mm (M6) long stud terminals allow secure connection of multiple heavy-duty cable lugs

Reliable Parallel Charging Without Voltage Loss

Diode-based battery isolators introduce a voltage drop of 0.6–0.7 V, which can prevent full charging unless the alternator or charger is voltage-boosted. The Cyrix-ct uses a high-current relay with negligible contact resistance, so your batteries receive the full charging voltage. This makes it a direct, efficient replacement for diode isolators in 12V dual battery systems and 24V marine setups.

Emergency Start Assist for Peace of Mind

If your starter battery becomes discharged or damaged, the Cyrix-ct can be manually engaged using a momentary push button or switch connected to the Start Assist terminal. The relay remains closed for 30 seconds, allowing you to draw power from the auxiliary bank to crank the engine. This feature is invaluable for remote travel, off-grid work sites, and marine applications where a flat starter battery could leave you stranded.

Designed for Harsh Environments

With an operating temperature range of -40 to +60 °C and an IP54 protection rating, the Cyrix-ct is built to perform in engine compartments, bilges, and exposed vehicle installations. The fully sealed housing resists dust ingress and water spray, while the robust M6 stud terminals accept heavy-gauge cable lugs for secure, low-resistance connections.

Typical Applications

  • Charging a second battery in 4WD, caravan, and camper trailer dual battery systems
  • Marine installations with separate start and house battery banks
  • Bow thruster and windlass battery charging
  • Commercial vehicles and agricultural machinery with auxiliary power requirements
  • Off-grid solar systems where multiple battery banks need to be combined during charging

Installation and Wiring

The Cyrix-ct features clearly labelled M6 stud terminals for Battery 1 (Terminal 87) and Battery 2 (Terminal 30), plus spade terminals for the negative sensing wire (Terminal 86) and optional Start Assist switch (Terminal 85). A wiring diagram is included in the product images to guide installation. For systems requiring multiple engage/disengage profiles, consider the Victron Cyrix-i 400.

Upgrade Your Dual Battery System with Intelligent Control

Replace unreliable diode isolators and basic voltage-sensing relays with the Victron Cyrix-ct 120A Intelligent Battery Combiner. Its trend-detection logic, bidirectional sensing, and emergency start assist provide dependable parallel charging for your auxiliary batteries. Order today to ensure your onboard power system operates efficiently and reliably, wherever your journey takes you.

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SKU: 59434215843

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Ember
Charlottesville, US
★★★★★ 4
Poor quality binding
Format: Paperback, Format: Paperback
Binding glue fell apart in less than a week and the pages fell out. Content is great though and I have a shiny new kernel based on Kali. 4 stars despite the binding because the content is top tier if you love all things Linux 🤌
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Reviewed in the United States on July 4, 2025
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S Navin
Draper, US
★★★★★ 5
An Essential Guide for Mastering Linux Kernel Development
Format: Paperback, Format: Paperback
Linux Kernel Programming - Second Edition: A Comprehensive and Practical Guide to Kernel Internals, Writing Modules, and Kernel Synchronization is an outstanding resource for anyone eager to understand the inner workings of the Linux kernel. Whether you're a beginner looking to get started or an experienced developer aiming to deepen your knowledge, this book delivers a well-structured and hands-on approach to kernel programming. The book starts with the fundamentals—setting up a kernel development environment, understanding kernel release nomenclature, and compiling the 6.x Linux kernel from source. As you progress, it dives into advanced topics such as kernel configuration, writing and debugging loadable kernel modules (LKMs), kernel synchronization mechanisms, memory management, CPU scheduling, and much more. Each chapter builds on practical examples, ensuring that readers not only understand the theory but also learn how to apply it in real-world scenarios. One of the book's biggest strengths is its focus on practical application. From exploring the kernel build process and bootloader configurations to working with Git for kernel development and troubleshooting system crashes using debugging tools, the book provides step-by-step guidance. The coverage of kernel synchronization techniques—including spinlocks, mutexes, and RCU—makes it an invaluable reference for those dealing with concurrent programming in the kernel space. Whether you're an aspiring kernel developer, a DevOps engineer, or a systems programmer, this book is a must-have. The clear explanations, well-structured content, and hands-on exercises make it a perfect companion for anyone wanting to go from a beginner to an expert in Linux kernel programming. Highly recommended for anyone serious about understanding and working with the Linux kernel!
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Reviewed in the United States on January 29, 2025
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Cliente Kindle
Lake Worth, US
★★★★★ 5
Broad, detailed and comprehensible book on Linux Kernel Programming
Format: Paperback, Format: Paperback
I got on my desk a copy of "Linux Kernel Programmin (2E)" by Kaiwan N. Billimoria and will shortly mention what this book is about. It is a book that you can read cover-to-cover to have a better understanding of kernel development, but I see also how it can be used as a reference when you are going to throw C code at your compiler and build a linux kernel. There is a number of scenario why you might want to do that: - You are recompiling the kernel for a new machine that needs better support - You are going to implement a kernel module and you need some context - You are going to work on the kernel yourself While all of those use-cases for the book are technically a fit, apart from gaining some higher understanding I see the most out of it if you are going to code on the kernel itself. There you have everything that is needed. You can go back and forth between your code and the book, and still learn by doing. What mostly impressed me is the breath of the topics: the chapter about writing a config file for the kernel enlists a total of seven (7!) different strategies to get started with a configuration file for your kernel. Also a lot of side tools are mentioned to help out with kernel development and debugging. Quite some module development can be in theory done without fully understanding the details of the kernel itself, but the deeper you reach, the more you will need the details that are well discussed in the book. Memory allocation, CPU scheduling algorithms, the book does not try to save words and describe in detail and plain language most things there is to know, not sparing plenty of references to other books and articles. Also, the material is up-to-date with the latest kernel.
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Reviewed in the United States on March 8, 2024
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Sergio Prado
Lexington, US
★★★★★ 5
For begginers and also experienced kernel developers!
Format: Paperback
There are a few aspects about the book that I really like. One is that every chapter provides a very detailed and immersive look into a specific part of kernel development. Another interesting aspect about the book is that it is based on a very recent kernel version (6.1), which is also an LTS version that will be maintained for a few years. I am not aware of any other book about the Linux kernel based on such a recent version. The first 3 chapters of the book explains how to configure and build the Linux kernel (both natively for x86_64 and cross-compiling for AArch64). After that, chapters 4 and 5 explains all you need to know about how to write kernel modules. And starting from chapter 6, the book introduces different aspects of kernel programming in very detail, from the scheduler to memory management and synchronization. Get ready, because it is indeed a big book, with more than 800+ pages! I really think the book targets both beginners and experts. For beginners, it will be a deep dive into major kernel programming concepts (make sure you follow along the exercises proposed by the author). For experienced kernel developers, the book is really a refresher. Though I work with the Linux kernel for 15+ years, I can still learn a lot by reading the book. An old dog can always learn new tricks, right?
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Reviewed in the United States on May 30, 2024
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princesscoldheart
Natrona Heights, US
★★★★★ 5
Organized well. You can read it section by section. Fantastic information. Clearly presented.
I like this book better than "what to expect" because this one does a better job of what you'll ACTUALLY expect versus telling you the throngs of horrible things that could happen to you or your baby. I'd rather be informed than mentally prodded with scary information. On one hand, it's good to know what could happen, so the other books you've probably already ordered are good to skim through, but this book I recommend reading all the way through. Easy to read, you'll actually have TIME to read it because you can read the age your baby is instead of a book that's all mixed up and organized by diseases and threats. Clear photos and explanations and tips on how to make your life and baby's life easier and better. I've understood my baby's needs better because of this book. I feel really glad I got it because it was the only book that really helped my daily life with my newborn.
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Reviewed in the United States on November 21, 2013

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