I have been using a cheap $3 charger from fasttech with my efest 18650 batteries and it has been working great! These batteries are only two weeks old and I have never disharged them excessively or dropped them. I left them on the charger overnight and woke up to them having a green light which means fully charged. I put them in my wismec 200 and they wont even register / or turn the device on. I then bought a new i4 charger and the charger wont read the batteries or charge them. What is wrong with them?! Does anyone have a similar experience?