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

Picture of 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

Picture of 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:

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:

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.


  • 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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.


  • 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.


cristhompson (author)2017-10-17

Brilliant. Been looking for something like this for a while. Is the tp4056 you link to the protected version?

lomo85 (author)cristhompson2017-10-18

No, the linked version is a unprotected one.

cristhompson (author)lomo852017-10-18

Thanks.. Would you mind linking in the protested one? I don't really know what I'm looking for... Ta.


jledwards666 (author)2017-10-12

This is kind of a side issue but I can't seem to make the first picture under Step 4 to parse correctly... what exactly am I seeing? Clearly the wire is being stripped but I've never seen a tool like that being used... it appears to be some sort of pliers with over-lapping rabbit teeth/prongs to remove the sheathing, with a hole in the lower jaw thru which a threaded part is protruded for some reason. The write up is clear enough as to what needs to occur during the step, I just can't get the picture to make any sense. Thoughts?

lomo85 (author)jledwards6662017-10-12

Yes, it is a simple wire stripper. It has two sharp v-grooves-knives and with the screw, I can adjust the remaining opening to the diameter of the copper. So, the plastic will be cut and can be strippt form the wire.

jledwards666 (author)lomo852017-10-13

Thnx, Lomo85, for getting back to me about this. I had indeed suspected it was some sort of stripper but was unfamiliar with the exact type. I've been an aerospace engineer for some 28 years and have never run across anything quite like these, although I've seem many, many other variants of wire strippers. Lol, I was so interested that I sent the picture to a number of my friends (also engineers) and none of them had seen these in person before either (although one of them had seen a picture of this style before in a book/magazine). He sent me a picture which I've attached herein. So, I learned something new today! Thnx again for the nice write-up. :-)

lomo85 (author)jledwards6662017-10-14

Yes, this is exactly the type I have.

billy_joule (author)jledwards6662017-10-12

It's one of the many different types of wire strippers.

WannaDuino (author)2017-10-13

das hast du gut gemacht, this is a very nice job dude.

mike.mcclure.3990 (author)2017-10-13

like the tartan......Well done.... Thank you

lomo85 (author)mike.mcclure.39902017-10-13

the tartan blanket is a souvenir from Kenia ;-)

Chuckwilcox (author)2017-10-12

Hi Daniel, great design, video and instructable thanks for sharing.

lomo85 (author)Chuckwilcox2017-10-13

thanks for your nice feedback!

MichaelAtOz (author)2017-10-12

Nice 'ible.

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

I know it's hot glue, but

"Step 5: Test the Charger THEN Glue the Wires in Place"

Always test before reassembling (or gluing), inevitably it doesn't work and you need to dissemble again...

lomo85 (author)MichaelAtOz2017-10-13

You are right! I already used the charger before I glued the wires in.

oldmanbreadboard (author)2017-10-12

I am just wondering what regulates your solar input to the 5 volts expected by the TP4056. The specs give some leeway, (4.35 - 6 V, 5 V recommended) but direct solar connections can vary quite a bit. I suppose if it works, it works but you could be shortening the life of the TP4056 and possibly your batteries if you have wide voltage swings. Just my conservative opinion. I like to stay as closely to specs as possible.

lomo85 (author)oldmanbreadboard2017-10-13

Thanks, my solar panel has a regulated voltage of 5 V. But you are right. If there are clouds the voltage can drop below. If there is no direct sunlight my panel has not enough power to enable the charger.

suncoaster (author)2017-10-12

Very nicely done. I have made several 3D printed battery packs for re-powering hand drills. Your instructable is a step up in this direction and I will be able to use your ideas in future, I'm sure. Thanks!

lomo85 (author)suncoaster2017-10-12

Oh, yes, this would be a great idea! I also have a 14.4 volt NiCd hand drill. Please send me a link if you have something which could fit.

suncoaster (author)lomo852017-10-12

If you'd care to email me at I'd be glad to do send you the .stl file that I used for my own 14.4 volt drill.

lomo85 (author)suncoaster2017-10-12

Thank you, also for the stl I received. It is great. You have to make an instructable about it.

AvensisA (author)2017-10-12

Deutsche hergestellt ist schön! :)

kassijussi (author)AvensisA2017-10-12

Not a German, from Bale I presume!

lomo85 (author)kassijussi2017-10-12

You are even closer, I'm from Bern.

lomo85 (author)AvensisA2017-10-12

I'm from Switzerland. But you are right, in the video, I speak German.

TimothyJ999 (author)2017-10-12

Nice project! A couple of refinements come to mind:

You can take a piece of the ground wire from a 14- or 16 gauge romex cable and use it for the internal wiring. It's dead-soft copper so it's easy to work with and holds its shape. You could also place it on a metal surface and pound it lightly with a hammer, turning it from a round cross section in to more of a flat rectangle. Then it takes up less room and the flat surface makes better contact with the battery.

Also, instead of hot glue, you could fill in all the grooves with epoxy, then after it hardens you can sand them flat.

lomo85 (author)TimothyJ9992017-10-12

Thanks for your inputs. I see, there is still a lot of room for improvements. I tried to do it in a way which works but is not too complicated.

RobertF168 (author)2017-10-12

Instead of hot glue I would rather use a 3D pen with the same material. This will be nicer when finished ;)

lomo85 (author)RobertF1682017-10-12

Yes, you are right, this would be perfect. but i did't have one.

About This Instructable




Bio: My Name is Daniel Aeschlimann. During the day I am a Mechanical Engineer. During the evenings I tinker with witn my 3D-Printer, my CNC router ... More »
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