DIY Battery Spot Welder - Demonstration & Explanation 

dude i love it thats the simplest welder ive seen ever thanks im making one today bro good stuff buddy !!!

Making use of the ru-vid.comUgkxcJ22tnHH9l1vjdIdEIG27iOG55P7LXI8 reconditioning plan, I just saved 2 auto batteries from being completely junked. The guides were very simple to follow. I wish I would have found this years ago! You may use the guide to recondition any battery type

Six years later, and here I am discovering this work of art. Thank you very much.

Such a simple, cheap but effective welder. Exactly what I'm looking for! Top stuff mate!

very cool, this just appeared on my recommended list, I have some batteries for drills that need repairing so this might just be a great find to make a spot welder. I had no idea how basic they actually could be. Now just have to "get around to" doing those jobs lol. Well done and well explained. 👍

Love it. So simple and effective for this type of spot welding. Thanks.

I like your minimalist approach. The advantage of a capacitor bank is you can control how much energy is stored and the caps can be recharged from a much smaller capacity current source. Need more current? Add another parallel cap. Usually they use FETs to dump the caps but I guess you could stay with the solenoid

Liked and subscribed. This is the simplest and effective one I've ever seen, so I'm definitely making one. Don't think of using that timer circuit. Einstein said, make it as simple as possible, but not simpler. This is the essence of genius!

Surprisingly effective! Good to know, refurbishing li-ion packs at home becoming more and more of a necessity.

Nice job, Kevin! Clear explanation and demo. Thanks for including the links for supplies! Gonna put this one to work fixing some old tools.

I built my own 3 years ago just like this and made a 24s 20p battery using Samsung 30Q cells, Worked very well! :)

Thanks for showing your welder. This is by far the simplest design on youtube and it works. I will certainly give this a try.

Nice one mate, I've just made one. Really handy bit of kit 👍👍

Outstanding, simplicity at its finest. Yet very effective, I'm glad I saw this video as I have some ni cads to replace instead of tossing a good tool. Like I like to say "If it's broke round here I fix it". Thanks for sharing

Clever; we haven't seen many of these with a battery. We shared this video on our homemade tools forum this week 😎

I can believe what i just saw. This is awesome, i have to try this ASAP. Thanks for sharing this video

Excellent explanations clear and to the point.

Great video fello! In this crazy time of self isolation (due to corona virus) i am planning to build a 13s4p and was going to invest in a welder. Now i know i have everything to make one, so why not!!!!

Best Hack I have seen for a **MINI WELDER** THANK YOU!

The simplest construction ever! Thanks a lot!

As a ham radio operator there are many times that I need to weld batteries this would save a ton not only in money but in time as well, thanks.

Hey great setup, effective and simple, just the way I like it! Thanks for the video!

This is great stuff. Well done. Top notch DIY!

I saw this this morning and being an old biker I had everything.👍 I put it together but using a car battery and it blows a hole in everything😁 I am going to look at putting the switch in some sort of rig so I can drop something on it and get it consistent by differing the drop height👍 Thanks!

Thanks for the video!! I just made my welder just like your video but I put the switch and relay on a board. It worked great first try! Looks as good as any factory made pack's welds. For years I have been trying to get batteries with tabs on them and soldering the tabs together or soldering direct to the battery which I know is bad. Now I can do the job neatly and professionally. Spent less than $20 for the nickel strip and relay.

You just saved me so many hours, thanks bro, I subed and told my friends of this gold mine

This is the best working DIY welder I have send. Great job

EXCELLENT Demo - nicely done and explained. Thank you.

fantastic! I've been looking at buying fancy welding kits for a while now

I'm very impressed. This is common sense at work. It saves hundreds of dollars compared to a lot of other methods using MOSFET'S .

Great job, very ingenious, I love when people share their creativity, thank you.

Nice home made spot welding tool! Thanks for sharing.

You're a star! The internet thanks you [for] sharing this great method.

I can confirm this works perfectly!!!! You saved me so much time and money thank you!! I got a 230 cranking amp battery from Walmart for $20 and a car solenoid from the local auto parts store and all set up for under $50!!!

Tremendous example of DIY success! Well done.

THANK YOU SOOOOOOOOOOO MUCH been looking for a cheap simple solution for years now!

Amazing welding, first time I know there’s such a welder !

Perfect and simple. Gonna make one. Thanks for showing this.

Simple and effective!! I always thought about building something similar. Time to dust off the work bench....

Good work darkkevind! Nice, neat, effective and a relatively simple design. Thanks for sharing, good video!

THANK YOU I am converting my longboard to be an electric one. I still need to build the battery pack as premade ones are either sketchy or really overpriced. Most of the spot welders out there are way to expensive for just one battery pack. I was about to give in and buy a premade pack when I saw your video. The solution is so simple that it never ocurred to me. Might spice it up with an arduino to manage the timing as I don't trust myself to nail that.

I almost posted about safety before watching the video to the battery part, I would have made a right fool of myself, this is an awesome on the cheap idea, my hat is off to you good Sir! I'm thinking of trying this myself.

Excellent video and battery spot welder simple and easy to use

nice effective yet simplest spot welding device idea seen by me so far. thanks for sharing

Also love the video was going to buy a spot welder but will just build one instead so thank you .

Such a simple, cheap but effective welder. Exactly what I'm looking for!

Dude thanks for this great vid, I actually made this tool to repair a bad battery pack worth close to $300. Spent about $30 in this and about $24 in new batteries. I had a tractor battery and my bro gave me some cable; I damaged three batteries in the process because 1. The nickel strips off eBay are very thin, (I know because I compared) so be careful ordering 2. I realized I held the button for too long jaja you have to be very patient it took me two hrs to weld 8 batteries mainly because the board from the pack I was repairing had a certain nickel strip position pattern on the old batteries so I had to weld it to match. I enjoyed the experience; thanks for this vid.

Increíblemente simple y efectivamente funcional, gracias por compartir

What a superb inspirational video! Thanks for sharing. I am an electronics engineer, so am mega impressed with the beautiful simplicity and frugality of this project. I intend to make one similar to yours. However, I do have a couple of thoughts to air. I am totally inspired to make one of these, but I will likely use 2 solenoid relays. Then if one fails and gets its contacts welded together (certainly quite possible, even if yours has not yet failed!). Then hopefully the other one will still always work and release ok. That way much less chance of a 'stuck' on quite dangerous situation occurring. It is unlikely that 2 solenoid relays could both fail with welded together contacts simultaneously. I would likely install one at each end of the battery. I believe this would make the whole thing that bit safer to use. It will also massively reduce the instantaneous contact breaking arc that will definitely be occurring inside of the solenoid just as the contacts are releasing. The second point is that I think you are taking the CCA spec of the battery (and the current rating of the solenoid) just a bit too literally. The battery CCA rating is *not* the absolute maximum current the battery can deliver. It is the maximum current it can safely deliver continuously, for a specified maximum period of time (typically a minute or two). The absolute maximum current it will deliver into a virtual short circuit (as in this case) will be very much greater than 200 Amps. I estimate that in this application, the momentary peak current is more likely to be in the region of 500-1000 Amps! Clearly the battery and the Solenoid relay are momentarily in severe overload. However, this is probably perfectly ok, as the duration is so relatively short. It would be disastrous if the solenoid relay failed to disconnect due to the internal contacts becoming fused together though. Hence why I suggest using two in series. Anyway, I'm definitely going to construct this. Please can I ask where you get the tab strip metal from, and what is the type and thickness? It looks ideal for this battery building project. Thanks again. Peter.

... Don't hot glue batteries together. Batteries heat up when they're under load. -- The glue won't remelt, but it will slowly flow, and end up in the wrong places in your projects over a few months of regular usage...

That is genus! I love it! I think the only thing I would do extra is maybe attach the switch to the side of your wooden jig you have there. Thanks for your great video!! Aaron

Awesome man, thank you! All I need to know to make one. Keep up the good work

Good use of materials.

As a teenager (more years ago than I like to admit), I managed to weld a spanner across the terminals of a car battery. All I knew was that it made a mess of my spanner... I never considered that there could be a practical application for the "technology" I had invented! :o) Nice useful video, thanks.

Hi, thanks for this video, I have referenced it in my recent upload. I have noticed with my setup that it's best to use a partly discharged battery, maybe about 12.5v so that the spot welds are not too fierce. Cheers

Very clever and simple, well done 👍

That is great. I was chewing my brain out to get a microwave thingy to get started. I'll do that one. Great idea. Thanks darkkevind

Thanks for the video! I’m in need of a battery spot welder, think I’ll build rather than buy!

thanks for actually explaining the power output for this. I would have thought 12V was a bit on the high side but your setup proves me wrong there ;o) perfect illustration of keeping it simple. nice.

Started to build my own battery welding station. I have almost all components already there, but had to order solenoid. One improvement I was thinking of, is to add a main switch between battery positive pole and solenoid to be able to cut off the circuit in case the solenoid melts down. It happened once on my daughters scooter and it was a little bit of a thrilling experience.

Thanks for the great video! I've purchased a starter solenoid and some short heavy-gauge battery cables, and I plan to give this a try in the next few days. Because I'm using a car battery which would normally have around 600 CCA, the high end of the range you recommended, I am going to use an Arduino Nano with a 5V relay similar to the one you showed in your video to operate the 12V coil for the starter relay. Since you have demonstrated the process is fairly robust with respect to timing, rather than build in a variable time capability, I will just run a series of trials by changing the arduino code until I identify a good interval value to use with my battery. The nice thing is that the 12V battery can also power the ardunio nano so it'll be self-contained and portable. I'll stop back here to let you know how I made out. Thanks again !!

In the US "twin and earth" wire/cable is called Romex® or its "trade name" non-metalic (NM-B) cable. 2.5 mm² is about 12 AWG and it is solid copper.

You just saved me hundreds of $$$ as I was going to buy a battery spot welder kit. thank you!

Wow, very simple setup, we really need this type of tequnics

3:37 was a good one, listening to the sound it seems like the faster the better. Great setup, I watched a electronics diy channel 'great Scott'. Don't know if you've seen his content. He made a few of these and they didn't turn out well, very complicated. Thanks for the clear explanation, I almost went with a diy pcb solution but this seems much more reliable.

Absolutely genius. Ta for the vid.

This is handy to know. When I had a job refurbishing starters as a lad, I made several critical welds using a copper clad carbon rod, (type that used to be used in movie theaters to produce the bright light cast upon the screen). The point I'm trying to make is that we used a car battery for the source of power to weld for that, so it will certainly do a great job for small spot welds as shown here. Thank you for the video, I'll be ordering some nickle to repack a few cordless shop tool batteries. 👍

This is a fantastic video, I now can’t wait to make one

Mate that was the best spot welder I've seen. I'm an electronic tech and have been trying to build a spot welder but could never get enough current. Yours is a simple and elegant solution. It reminds me of an old NASA engineering story; when they were in the middle of the space race with the USSR, NASA was spent millions designing gravity free ball point pens. Russia used wax pencils.

Nice setup. Ive tried using a microwave transformer and got it to work but it was putting out 900-1000amps and it i wasn't careful it would blow holes through the battery tabs. I think I'll try this setup.

Brilliantly simple design!

Please never stop tying knots wise fellow for I can see me fishing with you for a long while

Just so you're aware, the CCA rating (cold cranking amps) is like the max safe draw from the battery over a few seconds period in less than ideal conditions ( 0 Fahrenheit i think) and still maintain enough voltage to crank a car (above 7.2v), so using this shorter pulse, in good temps and ignoring voltage drop, the current is highly likely to be more than 200A as a direct short. Not saying this is a problem or anything assuming the battery doesn't start gassing or anything, just that if you're expecting to get 200A and are basing calculations on that, it might be good to try and capture the max draw maybe using a scope on single shot mode and a clamp meter as its highly likely to be well over 200A. Once again, im not being in any way critical, i love the project you've done there and its good to see people not just buying cheap unit that are really over priced for what they are, much respect for doing it yourself, i just thought the info may be useful.

You can also make a larger one using the transformer from a microwave. This is great for small jobs. Nice description of how you did it simple and effective.

Wonderful. Thank you for the demo and explanation. Cheers .

May positive energies and will power surround you. Thanks from Danville, V.A Jeff

Wow that so cool. Good idea, THANKS for the video. 👍🇮🇳

Extremely useful for those of us who use radio battery packs..only spot welding will yield compact replacement battery packs that will fit the dedicated space available. Thank You ! you don't specify the type of metal the strips are fab'd from ..??

Amazing how simple this is !

Awesome, just what I was looking for, thank you! New sub!

Great tutorial, I've tried many times to solder these with zero success so might give it a go, thanks

Something to be said for SIMPLICITY!

You do have that down to a fine art ..incredibly neat to .Thankyou for sharing

With regard to your possible use of a timer. I used one like that and very quickly found that the relay is not nearly as robust in terms of amp handling as it boasts. The little blue box relays are not really robust enough. The contacts fail. I switched to one using powerful mosfets and, of course, variable timing circuit included. I did not rely on the heat sink provided which was a slab of the circuit board material. I added a decent heat sink with fins etc. in the end I detected very little heating anyway. Frankly, your set up works so well I would stick with it. Simple. Robust. Good job.

Nice way simpler than I thought 💭

Hello Darkkevind1978... great video. I am contemplating making my own packs for an electric bike. Question : how often you need to charge the 12V battery or how many welds you estimate from one charge ? Thanks!

Hi, All I can say (well write) is outstanding & thank you for sharing (all the information) ! :D

i love your little DIY spot welder IF i ever get into building Li packs i'm going to copy this thank you

i love it, so this is how you do ti ey... nice

Two quick possible improvements, first is a foot pedal so you can use both hands and the other is a better handle (think soldering iron with 2 tip and when you press hard it activates the solenoid.)

thanx for the vid very informative and straight to the point unlike most here.

Awesome simple design thanks, I'll give it a go

May I ask what is the strip made of an stainless of nickle or pure?

wow, that looks too easy! how do you control the timing? I didn't see the timing board when you showed the battery, do you just press and let go fast?

Cool setup, I recently got the kweld unit, can’t wait to get it set up.

Looks like some proper work holding would speed the process immensely. Great video!

This reminds me of the time when I arced my metal watch band between the body of my car and the positive terminal of a 600 amp battery right next to the fender. I must have got the world record in getting a watch off. Still have the scars after 30 years.

Congratulations ! very good video, thanks for sharing, I'll be doing an equal for me.

Dude, great video, such a simple set up. I was going to end up mashing up a microwave transformer to do these batts, so much easier. ty

I have a deadly mains version of this. A 20 W CFL buld in series with 1000uF capacitor . I used a engine starter relay which complete the circuit and dumps that mains voltage charged capacitor into the spot.