Threaded Flashlight Tube Extension To Fit A 18650 Battery (25mm tube)

thingiverse

Here's a simple tube extension that can be used to upgrade an inexpensive LED flashlight. The standard battery compartment holds three AAA batteries in a caddy, and these caddies are often used as substitutes for 18650 batteries, making it a good idea to do the reverse. As a bonus, you'll get a significant increase in battery capacity. Ideally, this extension should be printed from one of the new conductive plastics, since the metal tube of the flashlight acts as the ground return path. However, I don't have access to that type of plastic, so the model has a hole through it where you can insert a piece of wire to create the contacts. After experimenting with both methods, I've found that using copper foil tape works well too, although the wire method is likely to last longer. Please see the post-printing instructions for more details on both options. Update: In my case, the copper foil method has proven durable enough to withstand several removals of the end cap. Considering how long a 18650 battery can last in this flashlight, I'm pleased with using the foil method. This extension is designed for use with a flashlight that has a tube diameter of approximately 25mm and thread spacing of 1mm.