NotATrainspott, you obviously have some detailed knowledge of battery powered road vehicles.
Perhaps you could assist with some ballpark figures as to how much onboard stored electrical energy will be required to move 36 tons 500miles over level ground at, say 50mph, and how that converts into batteries, especially the weight which, of course has to be deducted from payload.
The ballpark figure is 1MWh, according to Tesla critics.
According to
this government lab factsheet, the 85kWh pack from a 2014 Model S has a mass of 545kg. With subsequent advances in pack design and battery chemistry, I think it's safe to assume a mass of 500kg for a 100kWh pack. A 1MW pack would therefore have a mass of about 5 tonnes. It's a structural member, so the chassis could be slightly lighter than a comparable diesel truck. The remaining traction package would weight significantly less than any comparable diesel truck.
When people criticise the idea of an electric truck, they always seem to focus on the absolute worst-case scenario. However, the amount of trucking which actually happens in that absolute worst-case scenario is a tiny percentage of overall trucking. If the range is only 500 miles, then the truck won't be good for taking freight from coast to coast. But, most freight only goes far less than 500 miles. If it loses 40% of range when it's minus 20, then that's not a problem when most freight doesn't have to go through minus 20 conditions. When the benefits of electric traction are so great, the minor loss of utility in a small subset of cases that the vehicle can go its entire working life without being forced to experience is not enough to make it non-viable.
A big blocking factor for people is that they think about these exceptional cases when they decide whether or not to buy an electric vehicle. The average commute is well within the range of an electric vehicle when using overnight charging alone, but people still decide not to buy simply because once or twice a year they travel a few hundred miles at a time. Tesla's success comes from making people no longer have to worry about these exceptional cases, because they're building the Supercharger network to allow exceptional travel. The Semi is meant for commercial operators who make factual investment decisions based on the things they know to be true. If your trucking needs absolutely do not require more range or capability than an electric truck can provide, and you would save a significant amount of money from switching, then there is no good reason not to. Since you're only doing it to make money, you can handle the exceptional cases some other way, like renting a traditional vehicle or sub-contracting.
It's like how there's still a case for electric locomotives when there aren't that many end-to-end electrified freight routes in the UK. The benefits of being able to use electric traction on the WCML and ECML are enough to justify the existence of electric locomotives which are otherwise useless when freight has to go somewhere else or there's some reason the wires aren't available.