I purchased some 5 volt batteries and a charger from a supplier on ECF. My battery charging red lights never go out. I just left the battery on for nine hours. Charging lights were red, and the battery was very hot. I am waiting for the supplier to contact me. But in the meantime I thought I would ask here if you think there is a problem. I tried two different batteries with the same results. They do work for about 4 hours of vaping, but is it safe to use them?