Maglite’s used(?) to be the king of flashlights ... So [Travis] decided to upgrade it to make use of the ever-so-common, 18650 lithium-ion battery. Not looking to purchase any components ...

Most tools sport rechargeable batteries these days, but there’s no need to toss that old flashlight: just replace the cells with rechargable ones! [monjnoux] had a 3-cell D-sized MagLite lying ...