[nativepaul]

I wouldn't worry about the wire size too much if it is for a car, you might see big peak currents with a 1717 in a car but the average current will be pretty low, I doubt it would be over 50A average and 12g can cope with that OK. Try it as is and if the wires get hot then think about changing them.

I am a boat racer and a car basher, sprint racing boats can pull big average currents 150A+ is not uncommon so 8g is necessary, conversely for endurance racing we have maximum battery weights including wire and connectors and much lower average currents @45A, and in ordeer to maximise the energy of the LiPo within the weight limit we often have to run tiny wires or solder connectors directly onto the tabs and shorten the balance tap wires, I have taqken dozens of LiPo packs apart for modifications of one sort or another.

There is no need to worry about welding wires on LiPos, the VAST majority are not welded but soldered these days, and while most tabs are alloy and need a special solder if you are reconfiguring an existing pack rather than building a pack from scratch normal 63/37 - 60/40 will do you fine as it sticks perfectly well to the aluminium solder that they have already applied at the factory so just don't clean all the solder off the tabs after you de-solder the old wires and use that as your pre tinning for the tabs, tin your wires in the usual way, heat the wire and apply that wire to the tab to minimise heat transfer down the tab into the cell and cool as soon as it hardens with a wet cloth.