Onboard charger — the component nobody compares

It is a piece of hardware with a rating, fitted at the factory, and it cannot be upgraded afterwards in any practical sense. Its rating is what limits an overnight charge.

Why it matters when buying

Manufacturers advertise fast-charging peaks and bury this figure in a footnote, which is the wrong way round for how most people actually charge. If the car sits on a driveway every night, the onboard charger determines whether it is full by morning; the fast-charging figure determines only what happens on the handful of days a year you drive across a country.

Two details are worth confirming before purchase. Whether the unit is single-phase or three-phase, because that decides whether a three-phase supply helps at all. And whether the version you are buying has the same unit as the version in the brochure — a larger onboard charger is a common way to differentiate trim levels, and an entry model can quietly carry the smaller one.

Related: AC charging · V2L · CCS2