The original battery is likely damaged due to over-discharge. To prevent it from happening again. we recommend loosening the head of the light for 1/4 turn when you put away the light or not plan to use it for a while. This disconnects the internal circuit and eliminates the standby current which slowly drains the battery. When using the light, the factory also recommends charging the battery when it can no longer support the maximum brightness or just once a week if occasionally used.