I'm pretty new to RDA/Mech vaping, trying to learn. My setup is Mutation x v4 RDA running a 0.11 quad coil build with a Vanilla mod clone and 18650 Efest and MXJO batteries. The problem is during a vaping session, after 10 minutes my batteries get pretty dang warm, not hot but close. I'll still vape on the same battery for 10 more minutes or so and it's about the same temperature, but still gives a ton of power. But I get nervous and try to let them cool off. Upon reinserting the same battery, now it's basically dead. What's happening and how do I fix it? Also, is the temperature thing an issue?