First of all, if you really want to assemble it yourself, I suggest you don't use 18650 or 26650 batteries as cells, because the battery requires too many cells. Once one is damaged, it is damaged. It will take a long time to measure one by one. Problem, second, to weld this type of battery you have to use a spot welder. It is recommended to use lithium iron phosphate batteries, which have large capacity and are not easily damaged. They are available on Taobao, I have bought 4 so far, 3.7V 10A. They are very durable and can be soldered with one. soldering iron. See the image below!
I wonder what the voltage is on your tram battery? If it is 48 V, then 13 pieces are required and the series connection has a capacity of 48.1 V 10 A. If it is 36 V, then 10 pieces are required and the connection in series is 37 V 10 A. Finally, sIf you have the money, you can also purchase a corresponding protection card, usually available from manufacturers selling this type of battery.
Before confirming the assembly, be sure to check the size of the battery, then measure whether it can be installed in the tram. If it cannot be installed, you can consider purchasing 18650 or 26650. If you like. use this type of lithium nickel cobalt manganese batteries, the capacity of each battery is very small, so you need to consider the number of strings and parallels needed. Not only is it difficult to assemble and not durable, but it's even more so. annoying if something goes wrong!