Got a new echo kit. Charged up battery #1. Great. Put battery #2 on the charger, went to sleep. At 2am there's a pop, a hiss, and I come downstairs to a room fool of noxious smoke. A bit of sleepy investigation turned up battery #2 in a corner, scorch mark on the floor, and the plastic end cap melted off... It vented with flame. Better than exploding I guess.
Scary.
Scary.