It sounds like you are looking for a flashlight with the following criteria: single mode, high brightness, long run time, good heat control, and compatible with 18650 batteries. Here are some options that you may want to consider:
- Fenix LD22: This flashlight has a maximum output of 1000 lumens and uses either two CR123A batteries or one 18650 battery. It has a regulated output for consistent brightness and good heat management.
- Klarus XT11GT: This flashlight has a maximum output of 2000 lumens and uses one 18650 battery. It has multiple modes and features a temperature control system to prevent overheating.