I didn’t discharge them first. I charged them with the rest of the packs I used during the flight. They were already at 4.18-4.2 When I placed them on the charger. Is topping them off like that a bad thing to do?
As for the fire it’s very volatile. There was nothing left of the bags or the battery accept ashes wire and some very small pieces that blew away before being burned up. I’d say it wouldn’t burn through the risers or lines because there so far foreword, but those holes in the carbon fiber where the prop tips go would let in a lot of heat as well as any of the other smaller holes. The flames were not straight up, they shot out to the sides as if it was under pressure.
I used an entire (large) fire extinguisher and it still didn’t put it out. Although it was much smaller after that. The flames started about 4-6 feet high and 3 ft wide and after about 30seconds of burning I put the extinguisher on it and by the time the tank was empty the flames were at about 6”-12” high and as wide as the pack itself. It started up again and didn’t stop until the mass of the battery was all gone.
Maybe adding a layer of Kevlar to the back pad of the harness might make things safer.