The semi has a battery with 10 times more KWh than a Model S car. Those weigh about 1,200 lbs each, so figure 12,000 lbs. battery weight. Regular semi can have 250 gals of fuel that will weigh 1,750 Lbs plus whatever the tanks weigh (200 maybe?). Cummins n14 will weigh 2,700, Transmission will weigh 700 lbs. Four batteries will weigh about 300. Radiator and cooling system might add 300. I'm sure I'm leaving out a bunch of stuff but just those items total to about 6,000 so we're up to half the weight of the batteries. Not quite as bad as it might seem at first.