1. The battery is out. Bluetooth headphones are battery powered. If the battery is out of power or damaged, it will often disconnect automatically.
2. The interference source is too strong. Bluetooth headset is working at 2.4g frequency, this frequency also has wifi router, cordless phone and 2.4g mouse. These are relatively strong sources of interference.
3. Bad headphones. In particular, refurbished headphones, just bought normal, with a period of time out of the problem.
Bluetooth headset charge for a while will automatically power off can be bad contact, may be broken, re-change it