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Thread. 1/ An important part of the dynamic in these Tesla fires is the G48 coolant. It's a pretty standard coolant that BMW used to use as well as a few other OEMs. It has a relatively high autoignition temperature, but will instantly ignite if it hits an open flame. See video:
2/ It's typically diluted 30-50% with distilled water. Tesla's service manual states a 50/50 coolant/water mix. But even with that being the case, it's still a very flammable solution in the presence of fire. See video below:
3/ That spray bottle dispenses 2/3s of a teaspoon on each spray, to give you an idea. So when the battery experiences a thermal runaway event, not only do you have the battery cells themselves rapidly burning and igniting other cells, but they're directly surrounded by
4/ 2 gallons of an ACCELERANT in the battery module alone. The entire system holds between 6 and 7 gallons of coolant, depending on the battery size and specs. You'll also see in some of these videos what looks like a puddle on fire under the car or leading away from it.
5/ That's what that is, the coolant burning. Along with some melted plastic, too, probably. Again, look at the minimal structural damage to the car that crashed today in FL. The driver should have survived. The 5 star rating would be revoked if the @NHTSAgov actually had balls.
Notice the trail of fire going to the tree that's snapped in half. That would be coolant on fire, trailing away from the car. 
As @phoennix10 will point out, setting fire to atomized liquid is far easier than a non atomized liquid. I don't have the capability (or permits, probably) to generating the kind of heat needed to set a gallon of G48 on fire. But I've seen lithium ions short out and burn live in
person before. I've actually used them to spot weld tabs on other batteries before in a pinch. When they short the heat is absolutely incredible. We're talking about white hot here. That x100 in a thermal runaway is more than enough to set liquid coolant on fire. Using a spray
bottle and a gas burner is simply a scaled down demonstration of what happens when a lot more temperature and coolant is involved.
