Alberta Land Rover Enthusiasts Club Forum
General => Non Technical Discussion => Topic started by: headdamage on July 30, 2023, 01:09 PM
as a firefighter, thermal runaway on an EV is a scary thing, hard to stop the process once it starts. I think as we get more EV in Canada we need dunk tanks for these things. A stat id like to know is percentage of EV fires to percentage of gas car fires based on number of EV and Gas cars. would be an interesting stat.
Quote from: Chris on August 01, 2023, 04:58 PM
as a firefighter, thermal runaway on an EV is a scary thing, hard to stop the process once it starts. I think as we get more EV in Canada we need dunk tanks for these things. A stat id like to know is percentage of EV fires to percentage of gas car fires based on number of EV and Gas cars. would be an interesting stat.
500 times more fires per capita ICE versus EV.
https://insideevs.com/news/561549/study-evs-smallest-fire-risk/amp/
Yea that's fairly significant! Thanks for finding that!
correct me if I'm wrong, but is it true that just dunking the vehicle is not enough and it needs to stay submerged for a lengthy period of time as well?
I believe submerging the vehicle keeps the fire from spreading but may not put it out.
Submersing the battery stops the fire. They need oxygen from the air.
There is also a trend to Lithium Iron Phosphate always from Lithium Cobalt Oxide (LCO) and Lithium Nickle Cobalt Oxide (NCA). These are a lot safer from a fire standpoint. They are also cheaper and contain less difficult to acquire materials.
@Apu @headdamage, John Is correct, dunking them in a water tank stops the fire from obtaining oxygen to continue burning. They do need to stay submerged for some time, a few days at minimum to stop the thermal runaway that starts EV fires.
What happens is, inside the each little cell, there's a positive and negative, they're separated by a non conductive sheeth, usually graphite, and an electrolyte solution, the passing of ions via the electrolyte solution between the negative and positive occurs during the charging and discharging process. If the sheeth wears away and creates a connection between the positive and negative, it creates heat, like a short circuit. When the cell gets hot enough and expands it bursts, it's then introduced to oxygen and catches fire. There's 1000s of those cells in a car, so if one starts this process it'll cause the adjacent one to overheat, Crack then fire. That's why they're hard to put out with a hose, it's hard to cool it down enough to stop that thermal runaway.
Hopefully these new batteries John mentioned will be getting some limelight if their safer.
yes, that is exactly what I have heard. that even after a good dunk they can still start up again. Thanks for the info.
What happens when an EV is in a flood and water gets into the battery, once the water level drops, your going to have more than a rust issue
Quote from: Alex C on August 03, 2023, 06:42 PM
What happens when an EV is in a flood and water gets into the battery, once the water level drops, your going to have more than a rust issue
It is no worse than what happens to an ICE car in a flood. In general, they are better suited and designed to not be damaged when submerged.
" Flooded EV? Electrical corrosion may not be visible, and an EV can experience thermal runaway hours or even days after flood waters recede"
"This means flooded EVs parked in garages or carports next to homes should be moved away from buildings. These cars should not be driven but must be towed. Experts cautioned that no car, whether electric of gas-powered, should be driven after flooding until it has been checked out by a professional"
Not a regular occurrence for most us to see your vehicle flooded, but probably good to understand how to handle equipment after a flood.
I am guessing the flood line is a bit lower on an EV as the batteries are lower than the typical intake on an ICE, vent lines, valves would probably help, but who knows how they hold up over time. ICE would be plugs or injectors out and bar over, fresh oil and your should be ok , or pull the motor and rebuild. if you get water in a battery my guess is you need a different skill set to inspect what's going on or wait for the runaway, but as a mechanic what would I know about electricity or batteries.
Some of the larger mobile equipment battery packs have a pack flooding water inlet, if the battery management system communicates that a thermal runaway is probable, a fire hose can be hooked up, and used to flood the unit if the thermal runaway progresses, the flooding just helps reduce smoke, temperature etc. as the runaway , runs its course.
Good read on the subject, or maybe just some google gibberish.
https://techxplore.com/news/2022-10-electric-vehicles-fireand-ian-experts.html#:~:text=If%20an%20electric%20vehicle%27s,discharge%20energy%20and%20heat%20up.
Now it would be cool to be involved in battery electric machines, i bet this one has a a lot of Duracell's under the hood.
https://www.caterpillar.com/en/news/corporate-press-releases/h/caterpillar-succesfully-demonstrates-first-battery-electric-large-mining-truck.html