Mag-Lite 3-Cell D Size Adapter for 18650 Lithium Batteries

thingiverse

For this adapter, you will need to machine the front and rear spacers from aluminum or brass. The dimensions are given in the drawing. The three (3) D cell alkaline batteries are replaced by two (2) 18650, button top, lithium batteries. I have used the unprotected type. The two 18650 batteries provide 7.4 volts compared to 4.5 volts from three D cell alkaline batteries, essentially converting the 3 cell flashlight into a 5 cell flashlight equivalent. I will use a LED Mag-Lite conversion bulb purchased on eBay. The following video explains the design, demonstrates assembly and installation into the Mag-Lite. https://youtu.be/6BcD2K7EjpE The 3D printed adapter holds the batteries and spacers in the correct position for easy insertion and removal from the Mag-Lite and acts as an insulating sleeve. The adapter, with front and rear spacers, provides positive contact with the Mag-Lite switch contact and the tail cap spring. The D cell alkaline batteries are rated 12000mAh. Alkaline batteries are expensive, tend to be undependable and are known to leak, which can ruin your flashlight. The 18650 batteries are rated 3000mAh. They will last longer than alkaline D cells when running a LED bulb and I expect the 18650 will hold its charge (unused, sitting on the shelf) 6 months or longer. I have designed adapters for 2C, 2D, 3C, and 3D Mag-Lite Flashlights. The 3C and 3D adapters hold two (2) 18650 batteries. To avoid confusion, each adapter is listed on Thingiverse separately. Other Mag-Lite adapters available: Mag-Lite 2-Cell C Size Adapter for 18650 Lithium Batteries https://www.thingiverse.com/thing:3465819 Mag-Lite 2-Cell D Size Adapter for 18650 Lithium Batteries https://www.thingiverse.com/thing:3473302/edit Mag-Lite 3-Cell C Size Adapter for 18650 Lithium Batteries https://www.thingiverse.com/thing:3473408/edit