I have two such lights, a one and five CREE XML-T6 bike headlights and a couple of battery packs. Neither light comes apart easily. The battery packs I own are exactly the right size to be made from four and six 18650 cells and there is no extra room for electronics. My bet is that the controller circuit is behind the LED module in the lamp head. Frankly I never use either light as I quickly became disillusioned by the battery pack and cord being a PIA to deal with. You might take your question to BudgetLightForums.com. There is a group of dedicated light modders there Flashlight Modding and DIY Parts | BudgetLightForum.com who would surely know the answer to your question. I generally use a CREE XML-T6 flashlight for my front light. Flashlight and secure flashlight holder (w/o 18650 battery) were well under $10. No cords, easy on and off, very secure, and plenty bright.