EV vs. ICE: Uses of Circuit Protection

The way circuit breakers are used in internal combustion engine (ICE) vehicles versus electric vehicles (EVs) is driven by one key difference: the power systems at the heart of each platform. While their fundamental purpose, protecting electrical circuits, remains consistent, the technical demands vary significantly.

Here are the key differences you should be aware of when designing for each system.

1. Voltage Levels:

ICE: Traditional combustion engine vehicles operate on a 12V electrical system. Circuit breakers in these platforms are built to protect low-voltage circuits such as lighting, ignition, climate control, and entertainment systems.

EV: Electric vehicles, by contrast, use high-voltage systems, typically ranging from 400V to 800V, with some reaching even higher. Circuit breakers for EVs must safely manage greater voltages and currents, while also supporting low-voltage protection for auxiliary subsystems. As a result, EVs require a dual-layered circuit protection approach—for both high and low voltage circuits.

2. Power Source & Distribution:

ICE: Power is generated via an alternator and 12V battery. Circuit breakers primarily protect auxiliary systems from overloads and short circuits.

EV: Power is drawn from a large high-voltage battery pack. Circuit breakers are essential not only for protecting auxiliary electronics, but also for safeguarding the traction battery, power electronics, and charging infrastructure.

3. Safety Considerations:

ICE: Circuit breakers protect wiring and components from overheating and fire risk caused by electrical faults.

EV: In addition to fire prevention, EV circuit breakers play a critical role in operator safety. With high-voltage components onboard, these breakers must include mechanisms to isolate power during faults or collisions, helping to prevent electric shock and enabling safe servicing or emergency access.

4. Regenerative Braking:

ICE: As regenerative braking is not a feature in combustion vehicles, no circuit protection is required in this area.

EV: EVs utilise regenerative braking to recover energy and recharge the battery while slowing the vehicle. Circuit breakers must accommodate this bidirectional flow of current, ensuring safe operation during both driving and energy recovery.

5. Charging Systems:

ICE: These vehicles rely solely on internal fuel and don’t require external charging, so there's no need for circuit protection in this area.

EV: Circuit breakers are an integral part of the charging system, managing high-voltage current flow between the battery and external power sources. They ensure safe connection and disconnection during both home and rapid DC charging sessions, protecting against surge and fault conditions.

6. Thermal Management:

ICE: Thermal regulation is important but generally not linked directly to circuit breaker performance.

EV: High-capacity batteries can generate substantial heat during charging and operation. EV circuit breakers must be designed with thermal management in mind, to handle elevated temperatures while maintaining reliability and safety.

In Summary

While circuit breakers in both ICE and EVs serve to protect electrical systems, those used in electric vehicles face significantly more complex challenges. From higher voltage requirements and bidirectional current management to thermal control and human safety, EV circuit protection systems must be robust, responsive, and intelligently integrated

If you’re designing for a vehicle platform—ICE or electric—and need support specifying the right circuit protection solution, we’re here to help: contact us today!

Or visit our circuit breaker partner pages; Mechanical Products & Optifuse.