Harbor Freight 18650 Flashlight Battery Adapter

thingiverse

If you're like me, you likely have a stash of Harbor Freight flashlights collecting dust. The issue is that they demand AAA batteries, which rapidly lose power. In contrast, I've accumulated numerous salvaged 18650 lithium ion cells just waiting to be put to use, recharged, and reused. So, I created this adapter. The sole non-printed component is a small wire needed to electrically link the flashlight tube and lid. It's inserted into the small hole through the adapter and secured by the threads of the flashlight lid (as shown in the top-down photo). Important warning: 18650 cells can be hazardous. Use this design at your own risk. I won't accept responsibility for any mishaps. Lithium-ion batteries can cause fires or suffer permanent damage from misuse.