explode

So I've got an RX200 that I ran with 3 18650 batteries for a month or so and never encountered any issues other than battery life. All of them are 3.7 volts but one is a 3000mAh 2800mAh and 2500mAh. Just wondering how close I was to a hand grenade?

Has anyone else ever caught there cotton on fire by accidently burning it too much...... I did....