kWeld - “Next level” DIY battery spot welder
It originally started as a one-off, but through continuous support from https://endless-sphere.com/forums/viewtopic.php?f=14&t=89039 and http://www.eevblog.com/forum/projects/guesses-on-what-i-am-attempting-here/ , I am now able to offer my solution as a kit for purchase.
Here are some key specs of my system:
Input voltage for welding: 12V – 30V
Extremely rugged MOSFET-based power switch and mechanical current bus design
Maximum switch current: 2000A
Power switch internal resistance: 120µOhm
Logic supplied directly from battery – no need for a separate auxiliary power supply
Central weld control algorithm uses a Joule metering approach instead of a simple timer, eliminating the need for two-pulse firing and providing more consistent welds – the amount of energy that is deposited into the weld spot is always kept constant
Ability to detect a failed weld, and acoustic feedback to the user
Manual mode, triggered from external switch
Automatic mode, accompanied with a warning sound and triggered with a 0.5sec delay, once the system detects that both electrodes are in steady contact with the weld material
Audible feedback of weld process completion
Numeric feedback from an executed weld, assisting the user to achieve best results: deposited energy amount, required pulse time for this energy, measured current flow, measured ohmic resistance of weld spot
It is not the cheapest solution on the market, but it has shown bullet proof stability. It is more than capable of welding 0.3mm nickel strips.
These videos show the system in action: