Introduction: Super Simple DIY Spot Welder Pen (MOT Battery Tab Welder Pen) 10$

About: I mainly take on projects I have seen here and put my own twist on them. I also like to take garbage or thrown out electronics and make something nice from them. I have no certain area of Expertise, I am new a…

I was looking at all the sites online that sold Spot welder pens and saw how a lot of them were put together. I came across a set that was cheaper than the rest, but still a little more than I could afford. Then I noticed something. Everything they used to make those pens, I already had on hand. Even if I was to repurchase everything the cost would be smaller than purchasing from the site I was on. So for under 10$ I made myself a great pair I use daily to this day. Here are the simple parts needed for this build. My cost was supper low as I already had the parts from previous projects.


3/8 Copper Lugs($1.63) x 2-

7× 0.5-3mm Small Electric Drill Bit Collet Mini Drill Tool Chuck Tools Kit($2.69) x 2-

K&S 7/16 in. Dia. x 12 in. L Round Brass Tube 1 pk ($3.59)

12" Piece of 2 gauge Silicon Wire($1.50)-

Was a spare scrap I had laying around, can be any gauge doubled up or bigger with some of the wire pulled out.

Shrink Tube I had from previous stock($.20 cents)-

Step 1: Drill Small Holes to Align the Bit, and Spot for Soldering Later

Using a 1/16-1/8" drill bit, I drilled holes to match the drill chucks Allen screw holes. I also drilled holes in the middle of the pipe, I cut at 6" and drilled a hole in the lug. These are places I will use to screw the drill chuck to the pipe and the others just make it easier to add solder later on.

Cutting the Pipe at 6" gave me 2 pieces the perfect size. You can cut your pipe to fit your needs. Some DIYers like smaller Pipe, or shorter. Just make sure to use the perfect size to fit the drill chuck.

Step 2: Take the 2 Gauge Wire and Cut the End for the Copper Lug Then Solder

Cut a smaller piece of the insulation, from the 2 gauge copper wire and then slide into the lug. Using a small torch, or strong soldering iron. Heat up the lug and add enough solder to make sure it is solidly connected to the wire. This is the reason I drilled a small hole in the lug. I have found using my small vise helps keep this in place while I solder and let it cool.

Step 3: Cut the Rest of the Insulation of Wire and Slide Into the Copper Tube, Then Solder

Place the wire next to the copper tube and add lug to get the exact size needed. Cut with Wire cutters and then remove the Insulation. Slide into the copper tube. I used a small screw in one of the holes to hold in place while I solder. Place back in vise and solder in each hole in the pipe. Remove the screw and solder again. Make sure to solder enough to fill the pipe to get a good connection. I again used a torch to help. You can use a torch or a very strong soldering Iron.

Step 4: Use a File to Clean Up and Get Rid of Flare, Screw in Drill Chuck

There was a lot of plastic and flux left over after I soldered. There is also a flare on the lug I did not want. I took a file and got rid of the plastic, flux, and flare. Then I tapered the small hole for the drill chuck. Then added a small screw with a flared end that fit the drill chucks Allen screws holes. You can remove these 2 Allen screws, as you won't need them for the project. I tighten the screw to hold the chuck in place.

Step 5:

Cut and add shrink wrap. I used black, but you could use one black and one red. Before adding the big piece, I added smaller pieces over the small holes where I soldered. Make sure to cover the complete welding tip for protection later. You could here add better grips or even tape. If you used a welder of any type, these get hot no matter what you do when doing larger batteries. with the added copper in the tube and the copper tubing, this should help with the heat. But this is the part, where you do what comfortable for your hands.

Step 6: Add Some Bigger Gauge Wire to the Spot Welding Pen and Enjoy!

This was sooooo simple and I am sure there is room for improvement. I can only hope this inspired you to take what you might have laying around and make something very useful. I make spot welders often and you can find those on my Youtube channel. I have been using these since I made them and they work great! Not bad for 10$ and a little work. What worked out for me, I had all parts laying around in my stock as I had extras from previous projects. Thanks for reading and I hope you enjoy. Please if you like my video, Like it subscribe and share!

Step 7: Thanks for Watching My Video and Reading My Instructable