Originally Posted by mizlplix
The single largest cost in the construction of an EV is the battery pack.
In both systems, you use the same cell capacity in the pack (which is set by your daily driving needs.) BUT, in the high voltage system, you need additional cells in series to gain that higher system rating, adding significantly to your build cost and car room to put them.
Not true. For the same power, a higher voltage system (AC or DC) uses less current, so you use lower capacity cells, but more of them. Lithium Iron Phosphate cells are basically sold per Ah of one cell, so the cost of the actual cells is the same for low or high voltage.
There are plenty of other costs when you go higher voltage, but cell cost is not one of them.
The other costs include cell interconnects and the labor to install them, BMS cost (if used), fuses are more expensive, you may want to use many more contactors to break up the pack into ELV segments (120 V or less), and above 600 VDC it starts getting hard to find components that withstand the higher voltage for long periods of time. Chargers and DC/DC converters above about 417 V (Elcon / TC Charger and MeanWell) are difficult to find, so you may need two chargers and/or DC/DCs.
There are benefits to the higher voltage of course; thinner cables, smaller cells are easier to fit into awkward spaces, and so on.