This went much faster than I thought. Four modules welded together ready for connectors and Lexan boxes.
A few things I learned welding these things together. My welder is not the best, with practice I think I managed to put together four good modules that should turn out to be a decent battery for my scooter. but with this kind of welder I always had the fear of having a bolwout welding the negative side of the cells. without really good timing on the switch, these blowouts will mess up the whole thing.
I practiced a lot welding on dead cells and then I practiced some more on this small battery I made for my son's scooter. Today I checked the voltage on that battery and one cell showed 0.778V. Second thing I learned, the cullprit was one blowout that happened making that battery. I thought it was fine as I could not see a hole through the can but there was one because it leaked some liquid and messed up the whole 6P string.
Third thing I learned, when a battery is welded together with plastic spacers to make it look all nice and factory made, you can't change just one cell without taking half the battery apart. which means, somehow breaking all the welds on the cells, ruining all of the Nickel strips and regrinding the cells to make them clean to accept new welds. Grinding them a second time will make the metal too thin I'm afraid to try to weld them back together.
These lessons make me say this here: when welding cells together, do it with very good equipment, wether it be a very high quality DIY welder or some of those expensive welders so that nothing messes up your cells. Because when they're welded together, you can take them apart once but I don't think you can do it twice.
could you post a quick pic of your controller label a buddy is questioning what his says against mine and would like a 3rd opinion just to see if there is any discrepancies between model years 
