Battery Spot Welder, WESTOBiG Portable Handheld Spot Welder Double Pulse 4 Combination Gears Adjustable 5000mAH Spot Welding 0.1MM-0.25MM for Iron/Stainless Steel/Nickel Strip /18650 Battery Pack

It’s not clear in the listing but this is made by FNIRSI. I have a couple of FNIRSI oscilloscopes which are well made and reliable and so I expect this spot welder to also perform well. Unfortunately the first spot welder that I received would not charge after one time. I contacted FNIRSI customer support by email and after a back and forth with me sending a video of the problem, they confirmed it was a hardware issue said I would have to return the spot welder. No problem since there is a 30 day free return. The new one arrived in about a week and it is working perfectly. I think I just got lemon and I don’t fault FNIRSI.The instructions are not great but with a little experimentation you can figure out how to use this device. I did about 50 welds using the supplied 0.1 mm nickel strip. First I welded a tab to a AA battery. Using a pulse length of 10 ms and 2 dots, it produced very strong and nice looking spot welds. I upped the pulse length to 15 and it worked ok but it did burn through the nickel strip a couple of times and made a big spark. Next I welded a strip to a lithium button cell. I tried a number of alterations to my initial settings but I found that 10 ms and 2 dots worked the best, at least for the materials I was using. The operation was reliable and consistent. I really like the automatic repeat function, referred to as dots. I found that the first pulse always made a spark but then the following dots were practically silent and made very clean welds.I tested using the welder as a battery pack and it worked fine. It can output up to 2 amps at 5 volts. I’m not sure I’ll ever use this as a battery pack but I will use the feature to drain the battery to 80% for storage.