18650 Battery Charger - Micro USB with integrated spring holder

thingiverse

I have a growing pile of old 18650 cells that I've accumulated from discarded laptop battery packs. With the help of eBay, I was able to track down some versatile USB 1S chargers. They're great tools. Fast forward six to eight months, and now that I have access to a reliable 3D printer, I can start using those chargers more effectively. A quick scan of "Thingiverse" revealed numerous options for creating custom charging solutions, which I eagerly added to my collection. This morning, I decided to print a new charger based on the design located at https://www.thingiverse.com/thing:2847497. The self-contained spring mechanism is incredibly reliable, and the battery fits perfectly. However, my existing Micro USB 1S PCB doesn't fit quite right due to differing dimensions and shapes. I returned to my collection and found a charger with an identical PCB at https://www.thingiverse.com/thing:2847606. This design features a correct PCB holder, but I'm not fond of the idea of using a bolt as a contact point, especially since some of my cells vary in length (some are protected, while others aren't). To address these issues, I imported both designs into Fusion360 and modified them to suit my needs. I hacked off the existing PCB holders from each design, then combined the two "Franken-Parts" and adjusted their dimensions to match as closely as possible. After some tinkering, I was able to create a functional charger that works for me. It may or may not work for others, and it's possible that someone else has already created something similar – which would render my efforts unnecessary. Nonetheless, it's all part of the learning process, and I'm happy to have gained some valuable experience along the way.