So [Travis] decided to upgrade it to make use of the ever-so-common, 18650 lithium-ion battery. Not looking to purchase any components [Travis] performed this hack using simple recycled household ...

An 18650 potassium-ion battery represents a category of rechargeable batteries that employs potassium ions as the charge ...

It’s just a matter of figuring out how all the pieces fit together, like in this clever mash-up by [bethiboothi] that takes advantage of the fact that the popular TP4056 lithium-ion battery ...