The Fireman Access is being touted as a significant safety feature and as such Renault have made all of their patents on the technology freely available. In fact Renault are granting free access to all of their electric vehicle safety patents [1].
Renault Fireman Access is an exclusive innovation allowing emergency services to put out a fire on an electric vehicle in roughly the same time as on a combustion vehicle. From a technical standpoint, an adhesive disc is placed over an opening in the casing of the vehicle’s traction battery, effectively sealing it for normal use. If the vehicle catches fire and the flames spread to the battery, the powerful jet from the fire hose dislodges the disc and drenches the cells in water – the only fast and effective way of stopping thermal runaway. In this way, a battery fire can be extinguished in just a few minutes, compared with several hours and ten times as much water without this feature. Fireman Access thereby enables firefighters to return to operational readiness more quickly. Seven patents have been filed for this system, which is now fitted on all the electric and plug-in hybrid vehicles sold by Renault, Dacia, Alpine and Mobilize worldwide.
Renault [1]
Allows for a battery fire to be extinguished in 10 minutes compared to 4 hours for other approaches.
In the image above their is a hole in the body in white under what appears to be the 2nd row seating area.
an adhesive disc is placed over an opening in the casing of the vehicle’s traction battery
Looking at this it would suggest that the burst disc is an adhesive pad and that this can be accessed from the vehicle cabin.
It is important to also see the complete approach and hence it is worth reading further into the system:
- Fireman Access
- QRescue – QR code on every vehicle that gives immediate access to the vehicle’s technical information (engine, battery location…).
- SD Switch – disconnects the battery from the high-voltage electrical circuitry.
Questions
This is a great initiative, but does throw up a lot of questions:
- Does this approach work with all chemistries?
- Does this work for all pack voltages?
- Venting of gases into the vehicle cabin through the adhesive patch prior to thermal runaway, especially when a number of designs are now Cell to Body.
- What is the post-quenching process?
- Are there design guidelines?
- What is the sign-off test procedure?
This post has been built based on the support and sponsorship from: Thermo Fisher Scientific, Eatron Technologies and About:Energy
References
- Fireman Access, an exclusive innovation by Renault Group, is now available with a free licence, Renault Media
- Renault’s trying to do with EV battery fire safety what Volvo did with seatbelts, TopGear
- Filling device for firefighters of a drive battery of an electric or hybrid vehicle, US20150056481A1
- “Time Fighters”: the story of a unique collaboration between Renault and the fire department, Renault Media
See also: Emergency Shutdown, Propagation Mitigation, Battery Disconnect Unit