Uploaded April 2019 | Updated September 2026, 8 hours ago

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First attempt to build a DIY spot welder. I'm trying to build a spot welder in order to connect the battery tabs to bus bars. I recently took apart a battery from a Smart Fortwo EV, electric car. I re-arranged the cells to make a 14s battery which will work with 48 volt systems. However, I have to connect the cells together to the bus bars.

In a previous video I attempted to solder the cell tabs to the bus bars. This failed to make a good bond. So now, I am attempting a DIY spot welder using a battery, relay, and momentary switch.

This has poor results and I can't use the spot welder in the current configuration. Any ideas on how to fix the flaws?

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