Here is the factory's recommendation on how to use and maintain IMR batteries.
The high current flow of an IMR battery puts heavy stress on the battery so the battery is more prone to be damaged. The factory recommends not to over-discharge the battery. Over-discharge usually happens when you keep using the light until the battery is totally dead and cannot even support the dimmest mode. Once over-discharged, the battery could enter a dormant status and will no longer be able to charge again.
There are two ways to prolong battery lifespan
1) Do not use up the battery. Charge the battery when it can no longer support the maximum brightness, or just once a week if occasionally used.
2) LED Flashlights, even when powered off, have a small standby current which will slowly drain the battery. When not using the light or storing the light for an extended period of time, slightly loosen the head of the light for half a turn. This will disconnect the light circuit and stop any battery drain.
Hope this helps.