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:

Step 1: Material You Need

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.

Step 2: Designing and Printing

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.

Step 3: Integration of the Circuit and the Wires

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.

Step 4: Build the Pole Contacts With the Wire

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.

Step 5: Glue the Wires in Place and Test the Charger

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.