I agree fully, test you batteries...I only use Efest lately with and I2 charger that charges to 3.7V max, sofar so good, haven't had any issues.Dude check my post it's under 18650 2500mah 3.7 volts. I posted pics of my hand. Hybrid apollo caught on fire. Once a battery heats up. For instance you fire and there is a short. The positive and negative coils / wraps within battery have shorted. The battery must be thrown away. 2 if you going to use mechs make sure there is many fuking air holes. Shorts do happen batteries can over charge. Shit does go wrong mechs are dangerous. I've now got a amp meter. I test all batteries. Good luck take care.