Innovative integrated design and 4000mAh power bank Builtin 4000mAh battery can also function as a power bank No need for a separate external expansion board; more stable operation Maximum welding current: 650A Rechargeable via USB with 5V out, TypeC charging port, and 5V in Important: Use a 5V 2A charger (or standard below) to charge the welder; damage caused by not following this rule won't be covered by the Color screen display and adjustable full parameters Color screen visualizes spot welding parameters in real time Realtime monitoring of preheating, pulse, connection, and interval Physical buttons allow precise adjustment of welding parameters as needed Package includes: battery welder x1, spot welding pen x2, nickel sheet x1, file x1, instructions x1 Double pulse spot welding for reliability Outputs a preheating pulse, followed by an interval, then the main pulse Preheating cleans the surface oxide and reduces spark splashing The secondary pulse improves welding reliability for firm, stable joints Copper tip design and easy operation Soldering pen tip uses pure purple copper, wrapped on three sides to protect the battery protection board One side exposed for convenient side welding Easy operation: place battery cells on the welding surface and adjust the expansion piece slider to clamp the welding position Included items Battery welder x1 Spot welding pens x2 Nickel sheet x1 File x1 Instructions x1 Practical use scenarios Assembling Liion/LiPo battery packs by welding nickel strips and cells Repairing or refurbishing battery connections and pack joints DIY electronics projects and rapid prototyping requiring reliable spot welding