First of all, the answer is yes, it is safe to 18650 batteries
But using 18650 mobile power is not necessarily safe. The main reasons are:
1, because the mobile power products as a whole, while 18650 batteries s just a part of him, is another important part of the PCBA, if you use poor quality PCBA mobile power conversion control panel, did not even let the charge overcurrent and over short circuit protection circuit, then there is definitely a safety hazard.
2, cottage mobile power: currently on the market a lot of low-quality small workshop production of low-quality mobile power, the pursuit of profit, the use of secondary batteries or demolition electromechanical core, product quality control and testing and other aspects of aging may be blank, so mobile power is certainly a security risk.
Summary: regular mobile power mobile power manufacturers of raw materials procurement mechanisms and strict product testing standards, so it should be safe. Advises consumers to purchase the regular manufacturers of mobile power products, refrain for the sake of small cheap and buy cheap copycat products.