General battery safety
Never store or transport your 18650 batteries without using a case. Carrying your 18650s around in your bag or pocket is dangerous as it is possible that the positive (+) and Negative (-) terminals may come into contact with keys or metal objects causing the battery to short which could result in fire or explosion.
Do not leave your (18650) Batteries charging unattended i.e when you are sleeping or out of the house. There is always a risk with lithium batteries due to the nature of their chemistry
If a battery is crushed, or shows any signs of damage, do not use it. If you notice any irregularities with your 18650s do not use them and dispose of them in an appropriate manner.
Dual / triple 18650 MODs - Marry your batteries!
In a dual or triple battery mod it is crucial that you marry your batteries together. This means to use the same make and model and purchase your batteries at the same time. These must only be used together from birth until death. It can be very dangerous to use unmatched pairs of 18650s and can cause one of the batteries to be put under a greater load which can result in venting, thermal runaway and fire
Also running married batteries prolongs the life of both batteries and ensure a safe and enjoyable vaping experience
Charge you batteries to full capacity before first use. When using a multiple battery mod it is important that you understand battery safety before use.