Hey first off sorry if this isn't the right place to post this I'm new to the forum. I have 2 18650 2500mah 3.7V batteries. One of which my friend recently gave me which he had been using. I used the battery a decent amount for half the day and when I went to charge it later that night the light the on the charger was still green. So I didn't think anything of it and took it off charge. Today I've been using the battery all day and when I got home I put it on the charger and the light is still green! The battery seems to be operating my build fine but somethings gotta be up. When I charge my other battery it does show red and then eventually green and I switch it on both slots of the charger with same result. The charger has a 3.0v and a 4.2v setting and I have it on 3.0.