Why did Bolloré’s Breton electric buses catch fire in Paris? – France



Why can an electric bus catch fire?

“Batteries are sensitive to three constraints: external shocks, temperature regulation so as not to cause thermal runaway and good balancing of cell charges”, explains to the Telegram Sébastien Elie, automotive risk expert and director of the sector. “Motors” of the Stelliant group.
Two spectacular electric bus fires on Friday, one in Paris, the other in Carcassonne, seem to illustrate this diversity of potential problems. In the medieval city, it is a shock with a bridge which seems to have damaged the battery located in the roof of the bus of the Turkish manufacturer Karsan.
In Paris, the Bolloré group’s “Bluebus”, manufactured in Ergué-Gabéric (29), was stationary when it caught fire, like another bus in the same series, on April 4. As a precaution, the RATP, which operates 149, has chosen to suspend their circulation pending a return of expertise from Bluebus. “Everything is examined, from the battery to the computer, including the structure of the bus and the environment,” said a spokesperson for the Bolloré Group sector in Ouest-France on Friday.

Do fires happen more often when buses are loaded or in motion?

“The most common risk occurs during recharging, when the batteries are under high demand,” replies Sébastien Elie. A finding supported by a study quoted by the specialist magazine Sustainable Bus: “It is suspected that the main source of fire is due to overheating of components induced by the load. Only 19% of the 125 investigated electric vehicle fires could be unanimously attributed to battery failure.”
The higher the charge, the greater the risk of overheating the batteries and causing fires.
In addition, Sébastien Elie claims to have “already seen inert batteries, removed from a vehicle, catch fire”.

Why are electric bus lights so destructive?

“Often, an electric vehicle fire starts with a lot of smoke. Nevertheless, on Friday’s fire in Paris, we saw the opposite: first small projections, perhaps due to short circuits and explosions of cells in the upper part, before degassing and the start of fire which was very quick”, comments Sébastien Elie.
The event was very spectacular and caused great damage. The reason ? Batteries contain a high energy density in a relatively small volume. And the greater their capacity, the greater the damage can be. Because of the many chemical constituents, the induced fumes are particularly toxic.

Are electric buses more affected than thermal ones?

“You shouldn’t be afraid. According to our statistics, electric vehicles do not present any more risks than thermal ones,” replies Sébastien Elie. “We talk about it a lot because the fires they suffer are spectacular and cause great damage”.
Example in the Paris region where the RATP operates 500 electric buses from three different manufacturers, Heuliez, Iveco and Bolloré, for a total fleet of 4,700 buses. How many burned? “In a year and a half, we now have 26 bus fires. Five electric, one gas and the rest (20) thermal,” said a union source in the newspaper Le Parisien on Friday.

Could Bolloré’s all-solid battery technology be to blame?

The Bolloré group has been touting its LMP technology since its inception
developed with billions of euros by its subsidiary Blue Solutions: “An entirely solid cell without liquid components, without nickel or cobalt with a lithium metal electrode”, a guarantee of longevity. Is it more at risk of fire? Blue Solutions has always indicated that it benefits from a “high level of security”, despite “its high energy density”, thanks to its absence of thermal runaway.
“We cannot say that this is a type of battery that is more at risk than another. But as they were distributed at much smaller volumes than those with lithium-ion, we do not benefit from the same decline. Above all, you have to investigate, understand whether it is a manufacturing, design, operation or maintenance problem,” says Sébastien Elie.

Does the fire of a Mercedes electric bus equipped with Bolloré batteries, in Stuttgart, support doubts about their safety?

On September 30, 2021, 25 buses were destroyed by fire in a depot in Stuttgart (Germany), including two electric ones, the damage amounting to several million euros. A month after the incident, German police believed the fire could have started from a charging electric bus, German news agency DPA reported. In the viewfinder of the authorities, a Mercedes eCitaro, optionally equipped with solid batteries from Bolloré, and delivered at the start of the year. “Unfortunately, there are hardly any exploitable traces, because the development of heat was very strong”, specified a spokesperson for the police, while indicating that the fire would have started from the roof of the bus, where there are The batteries. However, the investigations promised to be particularly long.
Is this German precedent just an isolated case? Yes, wants to believe Sébastien Elie: “When we look at the problems of electric bus fires, we realize that each time, we never really have the same causes, they are very random”.

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