Car battery spot welder

I have all the materials on hand for this type of welder, I know it’s not ideal but it didn’t cost me anything. I’m using my jetski battery and starter solenoid, I watched a YouTube video, the guy was just tapping the momentary switch, everything worked out great for him, but me on the other hand, no matter how quickly I try to tap/release the button I’m blowing a hole in my nickel strip, I even stacked three together and blew a hole in them. I’m thinking of getting an Arduino off the shelf and trying to time it precisely. Anyone have experience with this?

So, there’s this progression that some people go through. Try to time it. Try using a 555 timer and a relay. try arduino and a relay. Then SSR. Eventually they end up with something like malectrics. :slight_smile:

Anyway, search a bit, on both our forums and in google. This is not a new path you’re treading.

I think you need a battery with less CCA. What is your current battery rated at?

260cca why would I need t upgrade relays? I’m not using it for the welding, just to time the solenoid.

Dont bother with arduino, buy a 555 timer module on ebay for $3~ and hook it up. I sell batteries on the forum and i use a homemade spotwelder with a timer like that. I am using an ac transformer though. Its a bit more complex to hook it up to ac power but it can be done. With a car battery it will be incredibly simple.

I’d really like to not purchase or wait for delivery. I already have an arduino atmega and a 12v relay board.

I’m pretty new to diy electronics, my coding is decent for a newb but where I get lost is in the parts like mosfets and such.

In the article above, What is the purpose of using a mosfet for switching? Why can’t I just code the atmega to switch the relay for the desired ms?

MOSFET driver for Higher switching speed?

Can you recommend a module?

Any module with high resolution timer, meaning it has options down to the milliseconds. The bad ones only go down to 100 milliseconds and that will still blast holes in your batteries.

Just search “555 timer”

I may have been inspired by the same video.


I went through progressively smaller batteries until I found one that made a nice weld. Super simple: car solenoid to some heavy battery cable and some sharpened copper rods. I forget what size the battery was a small atv 12v…

You can tell you have a proper weld when the material around the weld tears before the weld itself gives.

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