How to Integrate Wires Into 3D-Prints to Build a 18650 Battery Charger

My goal was, to build a battery charger for 18650 Li-ion batteries. For this project, I designed a 3D-printable part where I can integrate the tp4065 charger board and the wires which connect to the battery terminals.

This method can be useful, for every 3D-print with integrated electronics.

You can also watch my Video about this Project:

As charging circuit I use a tp4056 li-ion charger. This charging module is cheap and available as a protected version to prevent overcharging the battery.

TP4056 on Amazon: http://amzn.to/2fDOQ5Z

The charger which I build is capable to charger 18650 Li-ion batteries. I guess you have some because you are interested in this Instructable.

18650 Li-Ion Battery: http://amzn.to/2fEHoYv

What you need is a piece of wire. I recommend not to use litz wire but a wire with one solid copper pliable wire. It is easier to integrate into the 3D-print.

Tools:

• Because it is a 3D-printing related project, you need a 3D-printer. (or a friend with a 3D-printer)
• For soldering your soldering iron.
• And for the wort with the wire side cutter, pliers, and cable stripper.

You can download my 3D-model, print it and go to the next step. Here I will explain you my thought to my design.

My goal was, to create a well designed, and print in one part battery holder with integrated charger circuit.

I wanted to integrate all the wires into the 3D-print. First because of the nicer look, but also to avoid any failures from improper installed Wires wile later usage.

The designed features:

• The battery snaps into its place due to the flexibly designed bracket.
• The cutout enables an easy grabbing for removing the battery.
• The bore is to attach the charger to my solar panel (See the Instructables)
• The TP4056 charger circuit fits into the pocket on the side.
• Trough the opening the status LED's of the circuit are visible.
• To create a contact on the poles of the battery, there are two holes to thread the wire through.
• On the bottom and top side are grooves to install the wire.
• And for bringing the + pole wire to the bottom I designed a boring through the part.
• For routing the wires to the charger circuit there are holes towards the soldering pads of the TP4056 module.

Now, I explain to you how I integrated the wires into the 3D-print.

• First I soldered two wires to the tp4056 charging circuit.
• Then I insert the charger with the wires ahead into its designated pocket.
• The positive wire I route upwards through the long 2mm boring.
• Now the positive wire points out of the top, and the negative wile out of the bottom.
• The negative wire has to cross the positive wire according to the grooves in the bottom.

Now we make the two pole contacts with the positive and negative wire to have a connection from the battery to the charger circuit.

• Both outstanding wires we can cut down to 5cm lengths.
• With the cable stripper, we remove the isolation from the outstanding wires.
• now we push the wire to one boring down,
• pull it with the pliers through,
• and push it through the other boring back
• and pull it tight with the pliers.
• The end can now be cut down again to a length which can be bent over and slowed into the groove.

With this method, you will get a good contact for the battery poles.

I used hot glue to ingrain the wires into the grooves.

With a multimeter, I made a short test if the polarity is correct and everything works.

As you saw on some pictures, I'm able to use this charger with my tiny solar panel.

I hope you got some inspiration and please send me some comments from you projects where you used similar methods to integrate electronics into a project.

Attention!

• The Charger has no mechanical protection against reversing the polarity of the battery.
• I recommend to only use 18650 Batteries with built-in protection circuit.