Two events motivated me to move my setup outside:
A friend had a charger malfunction that lit off 6 lipos. He used a bunker setup and had no fire damage but his home was rendered uninhabitable due to the toxic smoke that spread throughout his home. His insurance paid for the hazmat cleanup and nobody was hurt but still...
I had a lipo puff on the charger at the field at our last big event. It didn't vent or explode but did get and stay really hot for a long time. I suspect that I was lucky, the battery reached a full charge before a catastrophic failure. I won't be charging my lipos in the engine compartment any more. I've bought a deep cycle battery for charging at the field.