I worked at a company who made charging points a few years ago and the consensus then was that the idea of charging on the road at petrol stations was outdated.
Chargers need to be where you park for an hour or more, so at the home, destination or basically where there are car parks.
But honestly what do you do when your application monolith outgrows its relational database. This seems to be the main reason to split concerns into their own services. Relational DBs don't scale horizontally.
Chargers need to be where you park for an hour or more, so at the home, destination or basically where there are car parks.