At some point later I got around to playing with DC fast charging ... That market still has a long way to go as far as sorting out its business model, as billing based on time vs energy is completely unfair ... An excuse that's offered less and less often is that pricing by kilowatt-hours delivered is prohibited in some states by utility regulatory rules.

I didn't know they were billing for DC charging in the US based on Time instead of kwh. Thats odd. In Europe its just kwh.

> In Europe its just kwh.

In the EU, yes. When you go to those dark corners of Europe that never achieved the membership, all bets are off.

In Montenegro and Serbia they charge per minute because the only entity allowed to sell kwh's is the national electricity company (in Serbia it's owned by Russia, so it is heavily legally protected).

It's almost all by the kWh here, but perusing PlugShare I've seen a few level 2 chargers here and there that charge by the minute. Usually that's a sign of a charger that was set up a while ago and is owned by someone who hasn't checked on it since.

I've never paid by the minute. Tesla Superchargers often deliver less energy per minute when they're busy (sometimes much less!) and it would be frustrating if they charged per-minute.

Other systems I've seen (Chargepoint) also seem to be energy-based.

The Supercharger network is well done. It's a shame that they took this long to open up to other car models because they really do get a lot of things right.

Arguably it should be both. Sitting and occupying a DC fast charging booth, especially once you're not charging at the full rate, represents an opportunity cost since someone else could be using it.

I think fast chargers in rush hour times will also bill for time to discourage long/slow charges on them. Naturally that'll vary on whoever sets the costs, but it does exist in EU as well.

In Europe, sometimes it's just kWh, other times it's kWh and time. After charging is done, it's just time.

I’ve charged in 30 states, it’s kwh every single time.