Can I leave my rechargeable flashlight or battery plugged in all the time?
The answer to this question is both yes and no.
All Fenix flashlights and Fenix batteries have protection circuits that should prevent any damage to the light or battery that could be caused by overcharging so it is possible to leave it plugged in all the time. However, it is a better option to just "top-off" your battery ever 15-30 days instead of leaving the light plugged in constantly. There are a few reasons for this:
First, for the total longevity (lifespan) of the battery, it is actually better for lithium batteries to not be fully charged all the time. Charging the battery up periodically or with regular use will not damage the life of the battery much but if you are constantly keeping it full without much use, it can begin to shorten the battery's life.
Second, though it is very unlikely, it is possible for the protection circuit in either the battery or flashlight to fail. If this were to happen then your product would be damaged or worse.
Third, leaving the light plugged in all the time wastes energy. The plugs that are used by most flashlights and battery chargers will constantly pull energy while plugged in, even if the battery or light it is charging is full. If you have the light plugged in at your home all the time you will constantly be paying for the electricity to charge the light, even if it is full!