Charging is where EV ownership differs most from a petrol car, and the jargon — AC, DC, kW, 10–80% — can be baffling. This guide explains how charging actually works, what the numbers mean, and why a car that "charges in 18 minutes" still takes longer to fill the last bit.
AC vs DC: the fundamental split
Batteries store direct current (DC), but the grid supplies alternating current (AC). Somewhere, AC must be converted to DC. Where that happens defines the two charging types:
- AC charging (home and most workplace chargers) sends AC into the car, and the car's built-in on-board charger converts it to DC. That on-board charger is small — typically 7 to 11 kW — so AC charging is slow but cheap and perfect overnight.
- DC fast charging (public rapid chargers) does the conversion inside the charger and feeds DC straight into the battery, bypassing the small on-board unit. That is how DC chargers reach 50, 150, 350 kW and beyond.
What the kW number means
Charging power is measured in kilowatts (kW); higher means faster. A rough guide: a 7 kW home charger adds maybe 40–50 km of range per hour, while a 250 kW DC charger can add that in a couple of minutes. The newest 800V cars push this into "flash charging" territory — the 5-minute and 9-minute claims you see on reviews refer to adding a big chunk of range, not a full charge.
The charging curve: why it slows down
An EV does not charge at full power the whole time. It charges fastest when the battery is fairly empty and deliberately slows as it fills, to protect the cells. This is the charging curve, and it is why almost every fast-charge figure is quoted as 10–80%: that middle band is where charging is quick. The last 20% can take as long as the first 80%, so on road trips it is usually faster to stop more often and charge to 80% than to wait for 100%.
What actually limits your charging speed
- The car's maximum rate — a car that peaks at 150 kW will not go faster on a 350 kW charger.
- The charger's maximum rate — and how many other cars are sharing it.
- Battery temperature — cold batteries charge slowly; many cars pre-heat the pack when you navigate to a charger.
- State of charge — the fuller it is, the slower it gets (the curve again).
- Chemistry — LFP packs can taper sooner than NMC in the cold.
Connectors, briefly
Chinese EVs use the GB/T standard; Europe uses CCS2; North America is moving to NACS. For buyers the practical point is simply to match the car to the chargers in your region — the underlying AC/DC principles are identical everywhere.
Practical charging habits
For daily use, charge at home on AC overnight and you will rarely visit a public charger. For long trips, plan around DC fast chargers and the 10–80% sweet spot. And remember that the size of the battery in kWh sets how long a full charge takes: a 100 kWh pack simply needs more energy — and time — than a 60 kWh one, whatever the charger.
