I had Google help me out with this one. For illustrative purposes, let's take the Tesla Semi (an electric commercial truck) battery. You could transport about 4 MWh worth of electricity. That's about 4 months worth of electricity for an average American household. Here's the details:

A single Tesla Semi utilizes an estimated 850 kWh to 1,000 kWh battery pack, which weighs approximately 10,000 to 12,000 lbs. If a trailer were filled strictly with these large, fully integrated packs rather than smaller, individual battery cells, only about 4 to 6 of these high-capacity, 1-megawatt-hour systems could physically fit within the weight limits of a standard trailer.

Battery Capacity & Weight: The Semi uses roughly 1 MWh, which consists of four, high-capacity, smaller packs.

Total Weight: A full 1 MWh pack weighs between 10,000 lbs (4,570 kg) and 12,000 lbs.

Capacity Limit: Due to weight restrictions of 80,000 lbs for a loaded semi (with a 2,000 lb increase for EVs), you cannot simply load 80,000 lbs of batteries into a trailer.

Physical Space: While the trailer has massive volume, the 10,000+ lb per pack weight means the trailer would reach its weight limit long before it is full of, say, Model S packs (if that was the method).