Battery safety is crucial for a great vaping experience! When mods were first created, the micro USB's primary function was not to charge the external battery cell, but to upgrade the firmware of the mod.
Some mods require external batteries to be powered. If your mod takes an external battery, it is recommended to charge the external battery cells in external battery chargers. Not only does it lengthen the life of your battery, it charges faster than it would via USB.
If your batteries are beginning to wear and tear but still holds it's voltage reading of 3.6V to 4.2V, you can rewrap them and keep using them. If your batteries are reading lower than 3.6V, it is recommended to replace the battery cell all together.
If you have any questions regarding external battery cell safety and charging, feel free to message us on Facebook or shoot us an email at firstname.lastname@example.org.