If you are like me then at some time in the past (or perhaps now?) you needed to secure an 18650 battery in a project but did not have an off the shelf holder available. In my case it was to power an led for a Focault Tester that I was building (instructable to come). Well, with some PVC and the remnants of a laptop battery (which is also a good supply of 18650 cells) we can make a simple holder for a single 18650 cell.
Step 1: Safety First!
18650 batteries can pack quite a punch! If you short circuit one you run the risk of heating up wire to a temperature that will burn skin, or cause a fire. It can also cause the battery to explode if there is no over current protection on the cell itself. Recharging them poses a risk as well. If they are charged beyond the rated capacity (4 volts or so) they can explode. Please be careful when you are working with these batteries. If not treated with care, they can hurt or perhaps even kill you or people you care about. You have been warned.
Step 2: Tools and Materials
You will need only simple hand tools for this build.
1) Coping Saw
2) Files and Rasps
5) Wire cutters
And a not so simple tool,
6) a heat gun with a well concentrated heat aiming
But you could substitute any well directed heat source such as a lighter, or a soldering iron to accomplish the same thing.
2) Metal foil conductor savaged from the battery teardown.
3) PVC Schedule 40 1/2" pipe
Step 3: Shape the PVC With Cutting Tools
We will shape the PVC in three ways.
1) Cutting away the bulk of the waste material with a coping saw.
2) Detailed shaping and finishing with files and sandpaper
3) Shaping the heat softened PVC with pliers
Start with a length of PVC that is suitable for your application. In my case that meant about 30mm longer than the actual 18650 or 680mm in length. If your situation dictates having two contacts, then make the tube an additional 20mm longer.
Mark the sides of the pipe with a sharpie and cut out the waste with a coping saw. If all you are doing is creating a battery holder then there should just be a spine and one or two tabs on the resulting PVC. If you want you can leave additional PVC as a mount point for other stuff, like a switch and an LED as in my case. The actual shape of the material that you leave behind is left as an exercise to the reader. What is required is one or two tabs beyond the loops you leave for securing the battery. What you are trying to get is a spine of PVC with two loops, one approximately 5mm wide at the bottom end and one that is more like 15mm wide at the top. The bottom loop will secure the battery against the negative terminal, and the top loop will be mostly cut away, and the tabs will be used as a gentle grasp of the top of the battery. The picture above shows the result after heating and bending the positive terminal (next step) . Smooth out the rough edges with files and sandpaper.
In this picture the tab that is folded up at the end. I did not take a picture of the result at the end of the cutting so at this point you should have one or two horizontal tabs that are in line with the spine of the holder.
Step 4: Shape the PVC With Heat
Then comes the softening of the PVC with heat and shaping the positive terminal ( of both terminals if that suits your application). I used a reducing adapter that I made for my heat gun so that I can concentrate the heat just where I wanted it. I just took a small sector of galvanized duct sheet metal and formed it into a cone that fit over the nozzle of my heat gun. I set the heat gun to high speed with a temperature of 350. PVC will start to melt at much lower temperatures so you have to be careful where and for how long you apply the heat. Let the heat gun warm up for a minute and then you can apply the directed heat to the part. It only takes a couple of seconds to heat the PVC to bending temperature. Quickly moving the part that you want to bend into and out of the heat stream will allow you to get some fairly controlled results. If you heat it too much the PVC will start to burn so be careful and perhaps practice on some scrap before moving on to the beautifully sculpted part that you have just created and are about to put the finishing touches on. Once the PVC is malleable you can shape it with pliers or a scrap rod or even with your gloved hand.
Step 5: Install the Terminal Conductor
Taking small sections of the salvaged metal film conductor you can create the terminals for your holder. Chances are that there are already some small tabs of torn metal on them that make great solder tabs, but if not, just cut the conductor to shape one. You can see a tab in the second picture and the third picture above. In my situation the aluminum was acting as ground but you can add a second terminal as well if your application needs one.
You might want to hot glue the terminal into place from the non-battery side.
Step 6: Finished
You now have a custom battery holder for your project.
This is my first instructable so any constructive criticism is welcome. If you make one be sure to click on I Made It. Thanks for reading.