For the last couple years I've been using a DIY spotwelder using a microwave transformer and a controller from avdweb.nl in The Netherlands to build E-Bike packs. Results were not that spectacular especially with thicker tab material and 26650 batteries. So I recently purchased the Kweld kit and used an Optima Spiral AGM 750CCA car battery as the power supply. It worked better but lugging that HEAVY battery around was a PITA. So, I have several A123 36volt modules that use 48 ANR26650M1A LiFePo4 cells in a 12s4p configuration. Each of these cells are rated to provide a 120amps load for 10 seconds and 50amps continuous. I purchased them from Battery Hookup, and normally use them in E-Bike packs. Battery Hookup gets them in regularly but sells out quick because they are only $49.99. https://batteryhookup.com/products/a123 ... 0910137476
I reconfigured the module into a 14.4 volt 4s12p pack and this thing kicks ass as a power supply for the Kweld. Way better then the 750cca car battery and super light. When I ran Kweld calibration it showed 1436 Amps during the short test. I just wanted to share this info with others.
I don't have a video on the battery build, just photos. So here goes.
With cover removed. There are several #10 torx screws holding the cover on, one under the label. Also remove 6 more screws to lift battery pack from the case. Removing the BMS requires cutting or unsoldering the connections along the edge of the board and unscrewing several torx screws. I cut the balance connectors with a knife and small snips. Be careful, don't cut yourself!
I removed the upper and lower cell holder plates to access the batteries. The lower plate is a pain because the 4 cells on each end are joined together with an external buss. I had to cut those sheet metal busses between each of those end cells (8 in total) and fold the metal up so the lower black cell holder plate could be removed. After that I had to separate cells to reconfigure the pack. I did not want to spot-weld new tabs to the batteries. Sometimes pulling the old tabs from these cells can perforate the cell. So I cut the cell tabs apart along the red lines shown creating 12 sets of 4 cell packs. The cells sets are highlighted yellow. I then repositioned them into the areas that are highlighted blue. I've only highlighted 4 areas, but they repeat throughout the pack. I used small pieces of nickel plated copper strips as jumpers to rejoin the cells but in a 4s12p configuration. I also doubled-up the strip to create buss bars across the 12 batteries on both ends of the reconfigured pack. They were soldered to the tab material running between the cells. The 0.3mm thick nickel plated copper strip came from https://18650shrinkandcellholders.com/
End view showing the two female output terminals. I disassembled the terminal assembly and soldered 8awg cables into them directly. Be careful, it's pretty easy to unsolder it from the board also. Oops, I did, but just had to wire wick the solder from board and resolder the terminal block back in.
I cut and reconfigured the heavy original copper connectors, soldered them to the battery and bolted them to the original output terminals at the end of the case. Used a short piece of 8awg wire for the positive connection.
8awg cables soldered into the output terminals. They go to the Kweld. Later on I may add a 4s BMS.