Features: There is a window on the back of the drive part, you can add copper or tin by yourself. The external pads for the LED and the on-board buttons are added to facilitate the connection between the LEDs & buttons on the board and other places. The upper and lower MOS design is bold and tinned to make the internal resistance smaller and the current stronger. Using 25V low internal resistance and high frequency capacitors make the power supplies more stable. Switch Function: press the switch for 1.5 seconds (green light flashes, low power spot welding pulse is output every 3 seconds); press the switch for 1.5 seconds (the blue light flashes and the medium power spot welding pulse is output every 3 seconds); press the switch for 1.5 seconds (red light flashes, high power spot welding pulse is output every 3 seconds); press the switch for 1.5 seconds to turn off the machine. This automatic trigger spot welding machine can weld nickel plating (0.1mm~0.15mm) of 12V lithium batteries and nickel-chromium batteries with a 90A~150A welding current. The following battery pack can be used as working power supply: the battery pack that can start the car can basically meet the power supply demand of this circuit, such as 12V car starting power supply, aeromodelling 3S high-rate battery pack, 3-string high-rate lithium battery pack, 12V 20A lead-acid battery with good performance, etc. Specifications: Material: PCB Color: Black System Voltage: 12V~14.6V Working Current: 90A~150A Suggested Battery (NOT included): 20~45ah lead-acid battery with good performance and low internal resistance 3.5~5.5ah 45C 3S aeromodelling lithium battery pack 30~35ah capacity 18650 battery pack Suitable for 18650 / 26650 / 32650 lithium battery Package Size: Approx. 190*110*30mm / 7.48*4.33*1.18in Package Weight: Approx. 200g / 7.05oz Note: Spot welding is based on local rapid heating and cooling with large current, which requires sufficient current supply. Generally, the welding current of 0.1mm~0.15mm nickel plated sheet is about 90A~150A, so the working power supply of circuit board must be greater than or equal to 150A. Packing List: 1 * Main Circuit Board 2 * Input Wire 2 * Output Wire with Welding Pen 1 * Welding Components Kit (tin straps + nickel sheets + copper insert ears + screws + heat shrinkable tubes)