Character Controller Collision

Hi guys,
for my player i use a character controller WITHOUT a rigidbody component. If i use a rigidbody my character flips around randomly even if the settings are changed. Now i want to make a coin. If this coin collides with my character it should get destroyed. The coin uses a rigidbody. Here comes the problem:

It does not/randomly detect the collision. I tried it with OnCollisionEnter() but that works, how I said, randomly. Most of the time I hit the object (so there should be a collision) but nothing happens. Sometimes I jump into it and it even gets destroyed. If I start the game and move the object towards the player he just gets pushed away. When I activate the gravity in the rigidbody component it gets destroyed if it hits the floor. I also tired the OnTriggerEnter() but that does not work. If I activate "Is Trigger" in the collider i just walk through the object. Any ideas? (sorry for bad english)

Thank you for your help.