What to Know About 'Fail-Safe' System for Electric Vehicles

TEMPO.CO, Jakarta - Electric vehicles are equipped with a "fail-safe," or an automatic security system designed to respond to engine or component failure.

Sriyono, a lecturer in Automotive Engineering Education at the Faculty of Engineering and Industrial Education at Universitas Pendidikan Indonesia (UPI) Bandung, explained that various considerations are taken into account while designing security systems for electric vehicles. "To avoid shutting down the vehicle over a small anomaly," he said on Thursday, April 30, 2026.

In general, electric cars will go through several stages of response, starting from giving a warning, limiting power, and entering limp or safe mode, and only then will they enter a total shutdown if the disturbance is deemed highly risky.

In electric vehicles, components such as the electronic control unit (ECU), electric current controller or PCU, battery management system or BMS, inverter, sensors, and communication systems, monitor the vehicle's conditions. "If an abnormal value is detected, the system will assess whether the disturbance is mild, moderate, or critical," said Sriyono.

As with fossil fuel vehicles, if a breakdown occurs, it is usually due to a disturbance in the main engine components and systems.

In electric vehicles, the safe mode is usually active because the battery is nearly depleted or the battery voltage is too low. Another factor is the battery being too hot or too cold, or the electric motor, inverter, or controller overheating. "The electric current is too high during acceleration, uphill driving, or carrying a heavy load," he said.

Another possibility is because the battery management system (BMS) detects disturbances in the battery cells. Or it could also be due to errors in sensors related to the gas pedal, temperature, electric current, or charging voltage. In addition, it could be due to disturbances in communication between electronic modules, or problems with cables, connectors, relays, fuses, or high-voltage contactors.

External factors also influence the triggering of fail-safes in electric vehicles. These include water puddles or floods that can cause disturbances in connector areas, sockets, sensors, high-voltage cables, batteries, electric motors, or controllers. According to Sriyono, the impact of collisions can also affect important components such as batteries, high-voltage cables, controllers, inverters, and electric motors.

Another possibility is below-standard current or voltage due to the use of a charger that does not comply with specifications, as well as modifications to the electrical system that defy the manufacturer's specifications or technical standards.

According to Sriyono, these various factors can cause the system in electric vehicles to detect unsafe conditions, then limit power or shut down the vehicle to protect the components and users.

"So many cases of electric vehicles shutting down are actually a form of automatic protection to prevent major components from being damaged and keep the users safe," he said.

Abdul Hapid, a Research Expert at the Transportation Technology Research Center at the National Research and Innovation Agency, said modern electric vehicles are equipped with various sensors and diagnostic systems that continuously monitor the vehicle's condition in real-time.

If anomalies are detected, such as communication failure between modules, sensor errors, or electrical insulation disturbances, the system will take action by limiting performance or even stopping the vehicle altogether.

"This approach is known as fail-safe, in which the vehicle prefers to stop rather than operate in potentially hazardous conditions," he said Thursday.

EV breakdowns are generally not caused by sudden failures, but are the result of protection systems working to prevent more serious damage or safety risks. This shows that despite the high electronic complexity of electric vehicles, their design approach emphasizes prevention and safety.

Read: Tesla Reclaims Global EV Sales Crown from BYD in Q1 2026

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