A detachable 21700 battery pack—a battery holder that doesn’t require a spot welder

BOM:

18650 spring contacts × 6 sets

M3 hot-melt nuts × 4 (I drilled holes of 3.7 mm and 4.5 mm, which are compatible with most M3 hot-melt nuts)

M3 screws with a length of 20 mm or more will work

Installation process:

1. Install the cover spring contacts (I used a 3-serial-2-parallel configuration, but you can also use 6-serial or another arrangement)

2. Install the main body spring contacts

This step is relatively tricky: I printed the part vertically and chose not to remove the supports (the internal supports couldn’t be removed anyway). Instead, I tapped it gently with a hammer and then soldered it in place using a soldering iron. Finally, I added an opening to the model to make installation easier (not yet verified)

3. Install the protective plate (this plate can be omitted; the protective plate can instead be secured with self-tapping screws around M2×6)

4. Secure all the covers; the new design has been modified so that all covers can now be fastened using M3 screws