The Aptera Forum
Don't know which epoxy Aptera is using for their body. But when I searched for ignition temperature of epoxies, all I found was melting, or more accurately, softening temperatures. In high heat, epoxies get soft, more like rubber, losing their strength. These are heats like 300 to 600 degrees F --- warm to very hot oven temperatures. Being thermally insulating, it would take quite a while for an extenal fire's heat to reach inside. I found no mention of ignition. Gasoline burns at 495 degrees F, so it would soften but not ignite the Aptera body. The vinyl wrap doesn't ignite until it gets over 700 degrees. So you'll just be roasted well done if you can't escape and no one puts out the fire. Don't worry --- you'll expire from the hemp smoke long before that happens. Don't let that happen.
Hi Harry. I live in a Marina with quite a few pleasure and commercial boats. We have had a number of fires over the last 15 years. You may have read about the pleasure diving boat accident where 34 people died in the nearby Santa Cruz Island. I have witness a half dozen boat fires personally. I can tell you that fiberglass/epoxy boats burn, and burn fast. They don't get soft and rubbery. There is a strong toxic black smoke that is emitted which can incapacitate you if you don't get out fast enough. There is plenty of video on YT, just search MV Conception. This one reason why many of the commercial boats are steel. One of our club members is a Coast Guard Captain and he has many stories to tell. Most fires are electrical with gas/diesel being second.
The problem with the completely enclose fiberglass composite shell filled with high tension wires (350 volts) and any number of components that could fail, overheat, or short out combined with flammable lithium ion batteries, could be a disaster with a bad accident. As I had pointed out earlier, if the car flips over during an accident, one could become trapped since the upward swinging doors would be blocked from opening. Once the black smoke happens, you have about one breath before succumbing to the fumes. I don't mean to sound gory, but one has to realize the potential problems dealing with all the accelerants within the same cabin areas. This is the same problem with the Corvette.
When discussing fires, one has to understand the uniqueness of lithium ion battery fires. LiPo cells are susceptible to the same troubles of other lithium-ion cells; overcharge, over-discharge, over-temperature, short circuit, crush and nail penetration can all result in thermal run away and catastrophic failure leading to explosion and fire. The electrolyte itself acts as an oxidizer making the fire almost impossible to put out. Water is not the way to put out a lithium ion battery fire. Our RC (radio controlled) club flies planes, boats and cars. We often charge and transport the higher amperage batteries in special metal boxes or insulated bags. This is because many RC batteries are pouch cells just like in cell phones. Samsung had a rash of fires in their Note 7 series. The Boeing 787 had early issues with the new replacement lithium batteries in 2013 causing spontaneous fires.
This is one reason I mainly use lithium Fe (iron) cell technology to avoid some of these issues. They tend to have a better lifespan, 50% more recharges and less chance of fire. The only drawback is less storage capacity per weight.
OK enough doom and gloom, lets see what safety factors Aptera comes up with. I am hoping that the windshield could easily be kicked out in case of being overturned and trapped.
@OceanDragon Thanks for the sobering education.
The answer is yes, if the temperature is high enough. The good news is that it would be rather unlikely to encounter an ignition source sufficient to start it burning.
What if the Aptera has a crash with a gasoline-powered vehicle that burst into flames. Would that be sufficient ignition? Does the shell material melt or ignite?
The fiberglass fibers themselves do not burn. The hemp fibers would. The epoxy resin would do a mix of melting and burning, depending on which one they use. The aerospace composites I have used have a flame retardant mixed in, so they mostly melt. You would need a crack in the shell with a jagged edge to really get them burning. The batteries, seats, carpets, and interior plastics would be a much bigger fire concern than the composite frame.
The shell is fiber-reinforced-epoxy, which does not melt. When we find the ignition temperature, let's see how that compares to our current cars' dashboard, seats, carpet, door panels...
Apparently fires occur in less than less than 0.5% of auto accidents, & EVs are even less likely to catch fire than gas cars.
My BEV battery is in a steel case very much like a gas tank, & in a similar location. Anything that would puncture it would likely puncture a gas tank, & based on the above plus gut instinct I'd rather take my chances with a battery.
So what I meant to imply was that for fire, driving an Aptera is likely better than driving a Corvette (or even getting hit by one in any other car) with its similar composite outer body PLUS all that flammable liquid gasoline.
Most cars (including the Corvette) have quite a bit of exterior plastic in the form of bumper covers, airdams, SUV wheelwell cladding, rocker covers, spoilers, fender liners, etc. I wonder how that is for burning/melting.
Without the approximately 80% waste heat of combustion, EV coolant doesn't get "scalding" like a gas car's does. "Body temperature" is more like it: I monitored my BEV's coolant temperature for a while, including in mid-90s Fahrenheit weather, & it never even reached 100F, & even that would still be safe. My EV battery is only rated to 125F, so when necessary, the A/C actually chills the coolant to keep it cooler than that.
Great points. Thanks.
What if a gasoline-powered fiberglass Corvette has a crash with a tree that bursts into flames. Would that be sufficient ignition? Does the shell material melt or ignite before or after all the interior materials?
Are you being sarcastic?
Do you not think that my question is legitimate?
I am not considering purchasing a gasoline-powered fiberglass Corvette.
@dhapp I think your question is a valid one. Any composite resin structure can burn quite easily once the ignition temperature has been reached. I am also concerned that scalding hot coolant might be circulating in the body shell to dissipate the heat of the batteries, motor, and inverters can be breached and spray into the cabin. One big source of ignition of the car in any distortion or breaking of the lithium cells; it is a horrible fire, once that gets started. https://www.motor1.com/news/359360/chevy-corvette-catches-fire-video/
There are several common risks for first responders associated with electric vehicle fires:
Electrical shock (up to 400 volts).
Extremely high temperatures and thermal runaway.
Lithium burns (respiratory and skin reactions).
Reignition up to 24 hours after initial extinguishment.
I was planning to keep some marshmallows in the motorcycle, just in case.
Now that you had brought up your concern, I may as well place my own here. I am worried about being trapped in the car when a fire breaks out. I once hit a foot long piece of rebar steel which was kicked up by the car in front of me. It badly dented the steel door sill. If that were to puncture the battery, you will have a spontaneous fire. If you look at the design of the car, if it were to flip and land in rocks or bushes it would be sit there on its roof. While the roof structure of the car may support the weight of the car and avoid crushing the occupants, it will also prevent the up-flipping doors from opening. Not a scene that I like imagining.