18500 AAA Battery Adapter

This is a battery adapter that I created that allows me to use a 18500 li-ion battery in place of the 3-AAA batteries in a flashlight. The forums I have read, said a 18500 battery can be used in today's tactical lights as a direct replacement. I found that not to be true, after buying the batteries and trying them. They weren't long enough, rattled, and didn't have a button to make good contact.

The 18500 batteries I am using are from Amazon: 18500 battery

My solution, add a cage which provides the button for the positive-end and take up the slop between the battery and the walls of the flashlight.

I created 2 basic types of the battery cage and included spacers to allow you to complete with what ever you may have around the house.

3 types.
- 18500_AAA_adapter with the 3mm spacer, add a M3x8 button head screw/nut
- 18500_AAA_adapter, hot glue half a pen spring (~3mm long) in the positive end
- 18500_AAA_adapter_w_nipple, use a 1/8" pop rivet (must reach top of nipple and inside the adapter about 3/8" shank)

Some flashlights vary, so I included a 1.5mm spacer so you can add it to the 18500_AAA_adapter to fit your needs.

Make sure, if you are using a spring, screw, or rivet. That the metal makes good contact on both sides of the center adapter.

As always, please use CAUTION when using Li-ion batteries. Do now allow the positive and negative ends to make contact directly or you run the risk of fire or explosion.

This is only used for my flashlights. I have not tried it for charging or other things yet.

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