Glossary

EV charging terms, explained briefly.

Short definitions for the jargon you see in the calculator and at public chargers. No essays — just enough context to make sense of a session.

Energy & battery

SOC: State of charge — how full the battery is, shown as a percentage.
kW vs kWh: kW is power (speed); kWh is energy (amount).
Usable vs gross battery: Usable kWh is what you can actually charge; gross is the full pack size.
Charging curve & taper: Power drops as the battery fills, especially above 80% SOC.
Preconditioning: Warming or cooling the battery before a fast-charge session for best speed.
Charging loss & efficiency: Not every kWh from the charger ends up in the battery — some is lost as heat.
Battery health (SOH): State of health — how much capacity the pack retains compared to when it was new.

AC vs DC charging: AC needs conversion inside the car; DC feeds the battery directly.
J1772: The North American standard AC connector for Level 1 and Level 2.
CCS: Combined Charging System — J1772 AC plus DC pins for fast charging.
NACS: North American Charging Standard — Tesla's connector, now adopted by many automakers.
CHAdeMO: An older DC fast-charging standard, mostly on Nissan Leaf and some Asian models.

Onboard charger: The AC-to-DC converter built into the car that limits Level 1 and Level 2 speed.
Level 1 charging: Standard household outlet — slow AC charging, usually 1–2 kW.
Level 2 charging: 240 V AC charging — the common home and public station type, typically 7–19 kW.
Level 3 (DC fast charging): High-power DC charging on road-trip networks, often 50–350 kW.

$/kWh vs $/min: Energy-based pricing vs time-based pricing at public chargers.
Idle, session & occupancy fees: Extra charges for staying plugged in after charging finishes.