BEC Systems

RC BEC Systems (Battery Eliminator Circuit) in Model Shipbuilding: Function, Pros & Cons

RC BEC systems (Battery Eliminator Circuits) have become an essential component in modern RC model shipbuilding. They provide safe, efficient, and space-saving power for onboard electronics—especially receivers and servos. In this article, you'll learn everything you need to know about BEC systems for model ships: how they work, when you need one, and what to look for when buying.

What Is a BEC System in Model Shipbuilding?

A BEC (Battery Eliminator Circuit) is an electronic circuit that takes power from the model’s main drive battery and converts it into a stable voltage (e.g. 5V or 6V) for the receiver and servos. Normally, these components would require a separate power source (such as a dedicated receiver battery), adding weight, space requirements, and complexity.

With a BEC system, you can eliminate the need for an additional receiver battery—hence the name "Battery Eliminator". This simplifies the setup, saves weight, and reduces the risk of power-related issues.

Types of BEC Systems in Model Shipbuilding

There are two main types of BECs used in RC ships:

• Linear BECs: Simple and reliable, often built into smaller models or speed controllers. Downside: inefficient at high currents, as excess energy is dissipated as heat.

• Switch-mode BECs (UBECs / Switching BECs): Modern and highly efficient, ideal for larger models or systems with multiple servos. They perform well under load and stay cool during operation.

Advantages of BEC Systems in RC Shipbuilding

Space and Weight Savings
No separate receiver battery means more room in the hull and less overall weight. This is especially useful in tight race boats or scale ships.

Efficient Power Delivery
Switching BECs are extremely efficient—even under heavy servo load.

Automatic Lipo Cutoff Protection
Many BECs integrated into ESCs offer undervoltage detection to protect your batteries and enhance safety.

Less Maintenance
Without a separate receiver battery, there's no need for additional charging, cable management, or troubleshooting dead packs.

Disadvantages and Risks of BEC Systems

Dependency on the Main Battery
If the main drive battery fails (due to deep discharge or connector issues), the BEC shuts down—leaving your receiver and steering inoperable. In the worst case, you lose control of the model.

Cheap BECs Can Be Unstable
Low-cost linear BECs may overheat under high load or deliver unstable voltage—causing glitches or system failure.

Heat Buildup in Linear BECs
High input voltages (e.g. 3s or 4s LiPos) combined with multiple servos can cause excessive heat without adequate cooling.

When Should You Use an External BEC Instead of a Built-in One?

Many ESCs come with a basic built-in BEC—suitable for beginners and small boats. However, an external BEC is recommended in the following cases:

• You're using more than 2–3 servos (e.g. in functional models).

• Your model runs on 3s or higher LiPo packs.

• You want to raise servo voltage to 6V or even 7.4V.

• You require redundancy and stability—especially in competition models.

BEC Systems as a Key Component in Model Shipbuilding

A good BEC system isn’t just a convenience—it’s the backbone of your model’s onboard power supply. Especially in complex ships with multiple servos and high-performance motors, BEC systems in model shipbuilding should not be overlooked.

When shopping for a BEC, look for reputable brands, sufficient current ratings (in amps), voltage configuration options, and safety features. And if you want maximum reliability, consider investing in an external UBEC with dual outputs—for added peace of mind on the water.