E-buses and new fire risks: a dedicated system developed by Dafo (within a EU project)

Dafo Vehicle is launching a fire protection system that aims at increasing safety of electric and hybrid buses with regards to fire risks. The product,  that is scheduled to be commercially available from 1st September 2020, has been developed in the framework of the EU-funded Li-IonFire (Automated e-vehicle Lithium Ion Battery Early Warning and Fire Suppression System) project.

Conventional fire suppression systems are in fact tested to be effective on vehicles with combustion engines, and all test standards are designed with this in mind. The growth of the electric and hybrid electric vehicle industry has accelerated the demand for new fire suppression technologies. Increasing demand for alternative drive vehicles goes together with the need to look after new fire risks, as knowledge is today limited about consequences connected to Li-ion batteries malfunctions, that could result in toxic gas emissions or explosion.

Li-IonFire project addressing fire risks for electric buses

The project partners, including Dafo Vehicle Fire Protection and RISE Research Institutes of Sweden, explored different techniques to detect potential battery failure, as early as possible, and take immediate action to stop, or delay, a potentially hazardous situation, Dafo explains.

The partners studied the various fire risks related to battery spaces, including specific risks when charging, and procedures for handling electric vehicles and batteries after a crash. They also investigated to what extent fixed and integrated fire suppression systems, which are widely used to protect engine compartments on heavy vehicles, can be applied to vehicles powered by Li-ion batteries, and how they should be designed.

A fire protection system for electric vehicles

Through extensive testing, the Li-IonFire team better understood how a breakdown occurs within the battery and how it can be detected.

“If a system is activated at this early stage, the battery can be ‘brought back’ to a safe state, without the fire developing further – explains Anders Gulliksson of Dafo Vehicle – The tests have also shown that even with a late deployment of the fire suppression system, there’s a possibility of delaying the battery reaching a critical state, meaning that the chance of safe evacuation is very high.”

The project team validated and demonstrated a highly innovative fire protection system for electric and hybrid electric vehicles. The new system provides an early fire warning system, and spot cooling to prevent thermal runaway while localising and suppressing fire.

Electric and hybrid buses, new fire risks

“With the rapid introduction of electric and hybrid electric vehicles in public transport, there are new challenges because they present totally different risk scenarios,” says Anders Gulliksson of Dafo Vehicle, coordinator of the EU-funded project. And adds: “When the commonly used Li-ion batteries fail through short circuiting, overcharging, high temperatures, mechanical damage and overheating, this might cause thermal runaway and the release of a flammable electrolyte, which makes fire extinguishing very difficult. In addition to the dramatic fire scenario with the rapid increase in heat, there are a lot of potentially toxic gases being emitted. Li-IonFire delivers to the market a product that didn’t exist until now: a system that can offer real protection against battery fires, using a new suppression agent, Forrex EV™, which is specifically developed for these applications,” concludes Gulliksson.