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 built-in buttons are added to facilitate the connection between the LEDs and the buttons on the board and other places. The upper and lower MOS design is bold and tinned to reduce the internal resistance and strengthen the current. The use of 25V low internal resistance and high-frequency capacitors makes the power supplies more stable. Switch function: press the switch for 1.5 seconds (the green light flashes, a 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 (the red light flashes, a 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 welding current of 90A~150A. The following battery can be used as the working power supply: the battery that can start the car can basically meet the power supply demand of this circuit, such as 12V car starting power supply, 3S high-rate battery for aeromodelling, 3 string high-rate lithium battery, 12V 20A lead-acid battery with good performance, etc. Features: Material: PCB Color: Black System voltage: 12V~14.6V Current 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 aeromodeling lithium battery 30~35ah capacity 18650 battery 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 rapid local 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 the circuit board should be greater than or equal to 150A. Packing List: 1 * Main Circuit Board 2 * Input Wire 2 * Output Wire with Welding Pen 1 * Welding Component Kit (Tin Straps + Nickel Sheets + Copper Insertion Ears + Screws + Heat Shrinkable Tubes)