Why the 20% ~80% range When We Say EV Charging?

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Charging your electric vehicle can vary in time, depending on the vehicle and other factors. In general, fast charging can take around 30-40 minutes to reach a battery level of 20%-80%, and around 1-2 hours for a full charge from 0%-100%.

Why the 20%-80% Range?

This range is the fastest for charging. The remaining 20% takes longer to charge due to the way electric vehicle batteries work. Here’s a rough breakdown: 0%-10% takes about 10 minutes, 20%-80% takes 30-40 minutes, and the last 20% takes over 40 minutes.

Charge time

This scenario is quite common during long trips when charging at highway service areas. Drivers often charge up to about 80%, avoiding the slower final 20% charge, and then recharge when their battery drops to around 20%. Of course, these are general suggestions and can vary depending on individual circumstances.

Factors Affecting Fast Charging Times

The fast charging times provided by manufacturers are ideal conditions and can be influenced by several factors, extending the time it takes in practice:

  1. Charger and Vehicle Power: Charger power varies, so choosing a charger with a higher power rating than your vehicle can speed up the process.
  2. Current Battery Level: Lower battery levels charge faster, and the difference can be substantial. For example, charging from 10% to 20% might take a few minutes, but going from 80% to 100% could take over 40 minutes.
  3. Battery Capacity: Larger batteries have higher maximum charging power, but if two vehicles have the same maximum power, the one with a bigger battery will take longer to charge.
  4. Environmental Temperature: Ideal charging conditions are around 25°C. Colder or hotter temperatures slow down charging, especially in freezing northern winters.
  5. Battery Type: Different battery types may influence charging speed. Lithium iron phosphate (LiFePO4) batteries might be faster at low levels, while ternary lithium batteries are quicker at higher levels.

The actual charging time is an estimate, considering the factors mentioned above, with each factor contributing approximately 5-10 minutes to the total time. Keep in mind that there are also unpredictable factors like waiting for other vehicles at charging stations, equipment malfunctions, app glitches, or poor network signals.

Slow Charging Times

Slow charging time depends on the amount of energy needed to fill your battery, as the charging speed (or power) is fixed.

To calculate slow charging time, use this example:

  • Vehicle battery capacity: 70 kWh
  • Current battery level: 30%
  • Required energy to fill the battery: 70 kWh x 70% = 49 kWh
  • Slow charging power: 7 kW
  • Charging time to full: 49 kWh / 7 kW = 7 hours

If using a portable charger with a lower power rating (e.g., 3.5 kW), it will take double the time:

  • Slow charging power with portable charger: 3.5 kW
  • Charging time to full with portable charger: 49 kWh / 3.5 kW = 14 hours

It’s important to note that the calculation for slow charging times might not be entirely accurate due to certain factors:

  1. Charging machine losses during current conversion result in slightly lower charging power.
  2. Areas with insufficient power supply might experience lower voltage, affecting the actual charging power.
  3. Extremely cold temperatures may require battery heating, impacting both time and charging capacity.

Taking these factors into account, it’s common to add another 10%-20% to the calculated slow charging time.

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