Cheap 18650 Spot Welder Reliability Mods and Test

These little 18650 spot welders can be found at several online retailers. Here are a couple of affiliate links if you want to help the channel:

► Amazon 18650 Spot Welder Better Option https://amzn.to/3mMv3Uy
► Amazon 18650 Spot Welder Original https://amzn.to/3NiR1J7
► Nickel Strips https://amzn.to/3o4QWtn
► Banggood 18650 Spot Welder https://www.banggood.com/custlink/3Dv...

The main issue seems centered on using batteries that sag under load. I've watched dozens of YouTube videos where the user connected the spot welder to some form of 12v battery and while attempting spot welds, the mosfets pop. The testing I've seen indicates they pop because of voltage drop across the control circuit causing the fets to not saturate during the duty cycle leading to failure. We saw something similar to this with the ESC testing I did not too long ago. The use of a capacitor between the diode and ground of the control circuit helps minimize voltage drop across the control circuit and allegedly prevents damage.

Here is a link to the reference video I found showing the issue and the solution:
   • Mini Spot Welder - watch/modify befor...  

The remaining mods: Reflowing solder on the negative trace, shortening the input leads, and connecting the positive welding pen to the positive input terminal are a combination of my own assessment, videos I've watched, and comments I've read about what happens when these fail.

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AFFILIATE LINKS
► Amazon Affiliate: https://amzn.to/3lEz5ZL
► Banggood Affiliate: https://www.banggood.com/custlink/3DD...

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