Reading a charging curve
Why peak power is the least useful number on the spec sheet.
You'll learn
- Explain reading a charging curve clearly and accurately
- Read the numbers that define the behaviour
- Apply the idea to a real charging session
Overview
Charging power is not constant. It rises, plateaus and tapers, and the shape of that curve decides how long you actually stand at the charger.
In depth
Charging simulator
Change chemistry, power level and starting temperature to reshape the curve.
Chemistry
Pack capacity75 kWh
Charger power150 kW
Ambient temperature20 °C
State of charge20 %
Driving / auxiliary load0 kW
Power accepted
150.0kW
Pack voltage
368V
Current
408A
Pack temperature
29.2°C
Efficiency
94.7%
Heat generated
8.32kW
Charging curve150 kW peak
0%50%100%
Time to 80%
18 min
Why the taper exists
As cells fill, their voltage rises and the driving force for current falls. Push anyway and lithium plates on the anode instead of intercalating. The BMS therefore reduces current progressively above roughly 60–80% state of charge.
Quiz
Curve check
- 1
Charging power stays constant throughout a rapid session.
- 2
Which number best describes real-world rapid charging speed?
Key takeaways
Remember this
- Power tapers as state of charge rises.
- Taper protects against lithium plating.
- 10–80% time beats peak power as a metric.
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