I have a Phantom P3 - so when I decided to build a quad - I opted from the same motors knowing them to be better (INHO) than most and at least I had props in stock!
The motors come with pre tinned wires - to which I added bullets...but thd wires would not "tin" so I just pushed them into ht liquid solder and let them cool before letting them free from the croc clips.
I recently had what seemed a faulty motor after the quad flipped on take off - which it did not do on its previous outing.
I bought a replacement.
While cutting the heat shrink off the "old" motor - the wire came out of the bullet, leaving a neat hole. Dry joint?? I cleaned it up, got a new bullet and soldered it in.
Testing showed the motor still had problems. I set about checking each wire and sure enough, out came another wire.
Same old problem I cannot tin the bare copper wire.
I have tried the modern lead free and also some 30 years old bits in the junk box which contain lead - neither would tine the wires.
What am I doing wrong
irons hot enough, used a flux pen, but nothing keeps solder on the wires.
UPDATE:
Seem to have found the answer. DJI apparently have their motor wires varnished ( water resistance???) I scraped then with a scalpel blade and got enough off to get some tinning applied.
Hope that helps others in future..