18500 AAA Battery Adapter

thingiverse

I created a battery adapter that enables me to use a 18500 li-ion battery in place of the standard 3-AAA batteries in a flashlight. According to forums, a 18500 battery can be used as a direct replacement in today's tactical lights, but I found this not to be true after purchasing and testing them. They were too short, rattled, and lacked a button for good contact. The 18500 batteries I am using come from Amazon: [https://www.amazon.com/s?k=18500+battery](https://www.amazon.com/s?k=18500+battery). My solution was to add a cage that provides the button for the positive end and takes up the slop between the battery and the walls of the flashlight. I created 2 basic types of the battery cage, including spacers to allow you to complete it with whatever materials you have around the house. There are three types: - 18500_AAA_adapter with a 3mm spacer and an M3x8 button head screw/nut - 18500_AAA_adapter with half a pen spring (~3mm long) hot glued in the positive end - 18500_AAA_adapter_w_nipple, using a 1/8" pop rivet (must reach the top of the nipple and inside the adapter about 3/8" shank) Some flashlights may vary, so I included a 1.5mm spacer to add to the 18500_AAA_adapter to fit your needs. Make sure that if you are using a spring, screw, or rivet, that the metal makes good contact on both sides of the center adapter. As always, use caution when using Li-ion batteries. Do not allow the positive and negative ends to make contact directly or you risk fire or explosion. This is only used for my flashlights and I have not tried it for charging or other applications yet.