We extremely propose using an external battery charger for 18650 battery mods, as it can help with well balanced charging and prolongs the lifetime of the battery and mod, for example from worn out microUSB port. That said, we did open a Geek Bar Pulse, taking all the mandatory safeguards. https://geek-bar03570.blogs100.com/31060885/the-fact-about-geek-bar-that-no-one-is-suggesting