AC and DC appear constantly in EV charging discussions and the difference between them is more important than most guides explain.
Here is what you actually need to know.
The core difference
The grid supplies AC electricity. EV batteries store DC electricity. Something must convert one to the other. Where that conversion happens is the fundamental difference between AC and DC charging.
With AC charging, the conversion happens inside the vehicle in a component called the onboard charger. The speed of AC charging is therefore limited by the capacity of that onboard charger commonly 3.6kW, 7kW, or 11kW on used EVs.
This is fixed hardware. It cannot be upgraded after purchase.
With DC rapid charging, the conversion happens inside the charger itself. Pre-converted DC electricity is fed directly into the battery, bypassing the onboard charger entirely.
This is why DC rapid chargers are so much faster the limiting factor becomes the battery's maximum DC acceptance rate rather than the smaller onboard charger.
Why it matters for used buyers
A vehicle with a 7kW onboard charger will charge at a maximum of 7kW from any AC source home charger, workplace charger, or public AC point regardless of how fast the charger itself is rated.
A vehicle with a 3.6kW onboard charger charges at 3.6kW from AC, full stop.
DC rapid charging speed is a separate specification entirely. Check both figures for any used EV you are considering, they affect how the vehicle fits into your daily and longer journey charging routine.
