u/Chance-Ad-1646

I'm using a zoyi zt n1 with a chisel tip(original tip it came with) and I can't understand why it's oxidizing so fast. I set it to 300°c (572 f)

And it turns almost black within 5 minutes of it reaching said temp.Am I doing anything wrong?

For context one of my friends gave me a lava 1s 450mah battery, when I took said battery to go fly with my air 75 it went from 4.2v all the way down to 2.9v within 10 secs of taking off. What should I do with this battery