Electric car glossary
The jargon of electric cars, in plain English.
- kWh (kilowatt-hour)
- A unit of energy. Battery sizes and electricity bills are measured in it. 1 kW for 1 hour is 1 kWh.
- kW (kilowatt)
- A unit of power, how fast energy flows. Charger speed and motor output are quoted in kW.
- Gross capacity
- The total energy the battery can hold.
- Usable capacity
- The part of the battery the car lets you use. Use this figure for range and charging sums.
- Efficiency (miles per kWh)
- How far the car travels on one kWh. Higher is better.
- Wh per mile
- Watt-hours used per mile. 250 Wh per mile is 4 miles per kWh. Lower is better.
- State of charge (SoC)
- The battery level as a percentage.
- AC charging
- Slower charging from a home, workplace or destination charger. The car's onboard charger converts AC to DC for the battery.
- DC rapid charging
- Fast charging where the charger itself converts to DC and feeds the battery directly. Power tapers as the battery fills.
- Type 2
- The standard AC charging connector in the UK and Europe.
- CCS (CCS2)
- Combined Charging System: a Type 2 connector with two extra DC pins. The most common rapid-charging connector in the UK and Europe.
- CHAdeMO
- An older DC rapid-charging standard used by some cars, such as early Nissan Leafs.
- Wallbox
- A home charger fixed to the wall, typically 7 kW.
- Mode 2 (granny) cable
- A portable cable that plugs into a 3-pin socket and charges at about 2.3 kW.
- Regenerative braking
- The motor works as a generator when you slow down, returning some energy to the battery.
- Pence per kWh (p/kWh)
- The price of electricity. Home, public and rapid charging all have different p/kWh rates.
- Off-peak (smart) tariff
- A tariff with cheaper electricity at set times, often overnight, popular for home charging.
- Charging losses
- Energy lost as heat during charging, commonly around 10% for AC. You pay for the energy from the grid, not just what reaches the battery.
- Rapid and ultra-rapid
- Rapid chargers start around 50 kW. Ultra-rapid chargers are about 100 kW and above.