I have to agree with the previous posts here, some people get a little too nutty-nuts about stacking batts! I do not know Anything about batts really, but people stack normal alkaline batts in flashlights, boom boxes, Walkmans, Discmans, and all kinds of new-fangled stuff. Lol. No, but seriously, they get carried away with it for sure with the mods. Proper venting, charging and running/stack switching your batts in pairs, metering them, monitored charging, and general inspection and replacement should make you as close to 100% safe as you can get! I never leave my batts unattended whilst charging, and pull them off when they are done. I meter them frequently to make sure voltages are correct. I inspect them for damage, and replace any that may have taken a hard fall. I also charge in pairs, and run them in pairs. When I am halfway through my volts when using I switch batts top to bottom in mod. I do not store mods with batts installed if stacked, or just pop one of the two out. I try to keep them (all batts) from sitting long in a hot car or direct sunlight. Most of this is truly probably not needed, but I do most of it all the time since I can. However, I have a way better chance getting creamed in my car on the way to work than any battery failure taking me out! What it comes down to is something that a ton of people seem to lack nowadays, good ol' Common Sense!