You don't say what the 18650 battery is, its use, its current? its C rating. 18650 batteries need a charger that looks after them, a USB or the type of charger you talk about isn't going to look after the battery.
Id recommend a
SKU 3514902 this will take care of your batteries
Kanger Subox Mini 50W, SMY Touch Box 100W , Vamo V5 15W, Coolfire 1, Eleaf 60W TC, Home brew e-liquid, Electrical, Mechanical Engineer.Born again vaper after 6 years