Spot welding of batteries for an electric bike is quite an ardous task. However, it pays back to do it on your own, because on this element we can save the most money. For example, the battery, which spot welding I will present, cost me around PLN 450 (~$115). Its capacity is about 570Wh (48V 13S6P, 12Ah), which is enough to cover about 50-70km by bike with an 18A controller (max 850W).