Feature · 4 min read
Rapid Charging & the Charging Curve Explained
Why a 200 kW car rarely charges at 200 kW the whole time.
What is the charging curve?
The 'peak charging speed' you see in the brochure — 150 kW, 200 kW, 350 kW — is the maximum the battery can briefly accept. In real life the speed rises, plateaus and then tapers off during a single charging session. The shape of that line over time is called the charging curve.
How does it work?
To protect the battery, the car's software constantly adjusts how much current it will accept based on temperature, state of charge and cell voltage. Power is usually highest between roughly 10% and 50%, holds steady for a while, then steps down progressively as the battery fills up. Above about 80% the speed drops sharply because pushing energy into nearly-full cells generates a lot of heat.
What does it feel like?
Plug into a 200 kW charger at 15% and you may briefly see 190 kW on the screen. By 60% it might be 120 kW, and by 80% it could be down to 50 kW. The 10–80% portion is what really matters on a road trip — that's why most manufacturers quote a '10–80% in X minutes' figure rather than 0–100%.
Benefits of understanding the curve
- ✓Compare cars more honestly than by peak kW alone
- ✓Plan trips around the fast part of the curve
- ✓Avoid wasting time charging past 80% when a second stop is quicker
- ✓Spot when slow charging is normal, not a fault
Limitations
The curve depends on battery temperature — a cold pack tapers much earlier, which is why pre-conditioning matters. Charger sharing, hot weather and worn cells all flatten the curve too.
Common problems
- ✓Cold battery limiting speed at the plug
- ✓Sharing a charger cabinet that splits power between two cars
- ✓Charger derating due to its own overheating
- ✓Confusion when a 150 kW charger delivers only 50 kW to an older EV