Well I've bought about eight of these Xanes SFL-01 headlights. The last two I bought by accident because I had forgotten that two were already on the way. One of them seems defective. It's a weird battery problem. After charging the battery, the light will last for the proper number of hours. But if I don't use it for a few days after charging, the battery is discharged. I guess that means there is a short circuit that drains the battery. At this price, I'm not complaining. I used a label maker to put a serial number on each unit so I can keep track of when I charged each unit, and it helped me detect which one doesn't hold a charge.