I've been salvaging these disposable vapes for the 3.7v 500mAh lithium batteries inside. They can be used to power small electronic projects with the appropriate charging circuit and voltage converter. : r diyelectronics Transform Vape Pen Batteries into DIY Power Banks for Your Projects JNR P4 Stellarc 100K Vape Kit Dual Pods, Dual Flavours, 64ml 500 disposable vapes recycled into a powerwall to power a house and workshop enough juice for up to eight hours of home usage or three days of work Tom's Hardware