Turn-key PCB assembly services in prototype quantities or low-volume to mid-volume production runs

Arduino based Spot welder for 18650 batteries

spot welder

Lots of devices are using battery packs that are spot welded together. Spot welding ensures great connectivity and vibration safe operation. In order to spot weld, you need special equipment that can give high current output for the very short time duration. This way you can get good weld joints without damaging the batteries with heat. Building a spot welder for small tasks is fairly easy. KaeptnBalu has shared his instructable where he assembles his spot welder which is controlled by Arduino Nano. Spot welder requires 7-12V power source capable to output high currents. So any lead-acid battery works fine. Arduino is used to controlling welding pulse duration which can be adjusted from 1 to 20ms. With 0.15mm nickel strips he found that 9ms gives the best result. First of all, he prototyped the spot welder and then built his custom PCB where he put 8 MOSFETs in parallel that switch current on and off. He also built plywood foot pedal switch to keep his hands free while soldering. If you get lost among welding terms, check out an excellent… Continue reading

AVR controlled spot welder

Spot welder may be a handy tool for many tasks. Let’s say you need to connect multiple lithium cells – spot welder is a perfect tool for that. Of course any thin enough metals can be welded together and by running high current on sport so they melt together. In this project a spot welder is made from battery charger. This way most of power electronics parts are in place. Other part is control that is made by AVR ATmega88PA. Putting high power AC and 5V logic circuits together leads to failures due to large interference noises, so special precautions has to be made. Ok, the simple idea is that microcontroller detects zero crossing of AC line and then fires SCR for a short period of time. AVR also measures a peak current with Hall Effect sensor. All data and settings are conveniently displayed on LCD screen in front panel. Continue reading