The electric-car dictionary

State of Charge

How full the battery is right now, from 0 to 100%. It's the EV's fuel gauge, not a measure of its health.

kWh

Kilowatt-hour

The battery's energy unit: how much it stores. It's the 'tank size' of an EV. More kWh, more range (all else equal).

kW

Kilowatt

The unit of power: how fast energy flows. In motors it's 'how much muscle'; in chargers it's 'how fast it charges'.

Usable vs nominal capacity

Nominal is all the energy that physically fits; usable is what the car lets you use, keeping a reserve buffer to protect the battery.

ΔV

Cell voltage spread

The voltage gap between the highest and lowest cell in the pack. A healthy pack stays tight; a wide gap betrays cells falling behind.

LFP

Chemistry

Lithium iron phosphate (LiFePO₄)

A rugged, low-cost battery chemistry, very common in Chinese EVs and entry trims. It handles daily use well and tolerates charging to 100% better than others.

NMC / NCA

Chemistry

Nickel-manganese-cobalt / nickel-cobalt-aluminium

The nickel-rich chemistries: they store more energy in less weight, so they deliver more range. They dominate mid- and high-end Western EVs.

Charge cycle

One full cycle equals using 100% of the battery, in one go or in pieces. Two 50% charges add up to one cycle; it's not 'every time you plug in'.

Calendar vs cycle aging

A battery ages on two clocks at once: time (running even while the car sits) and use (the charge cycles). The two add up.

WLTP

Worldwide Harmonised Light Vehicles Test Procedure

The European lab test for range and consumption. It's more realistic than the old NEDC, but it's still a controlled exam, not the road.

EPA

US Environmental Protection Agency cycle

The American range test. It's usually the closest to reality of the big three, because it includes more highway driving and air conditioning.

CLTC

China Light-duty Vehicle Test Cycle

The Chinese lab test. It tends to give the most optimistic range figures because it includes lots of slow city driving and little highway.

NEDC

New European Driving Cycle

The old European cycle, now retired. It was notoriously optimistic, so take its range figures with a grain of salt.

Real-world vs rated range

Rated range is the lab-test figure (WLTP, EPA, CLTC); real-world range is what you actually get on the road, almost always lower due to cold, speed and climate.

OCV

Open-circuit voltage

The battery's voltage at rest, neither charging nor discharging. Its relationship to charge is the 'fingerprint' that betrays the chemistry and the cells' state.

BMS

Battery Management System

The computer that looks after the battery: it watches each cell's voltage, temperature and balance, and it's the one that reports the SoH you see in the car.

Heat pump

An efficient climate system that moves heat instead of generating it. In winter it can save a good chunk of the range that cold eats.

AC vs DC charging

AC (alternating) is the slow charge at home, capped by the car's onboard charger; DC (direct) is the fast road charge that goes straight into the battery.

Charging connectors (Type 2, CCS, GB/T)

The EV's 'plugs', and there's more than one. In the region Type 2 (slow) and CCS2 (fast) rule; watch out for cars imported straight from China, which can carry the Chinese GB/T connector, incompatible with local chargers.

Regenerative braking

When you lift off the accelerator or brake, the motor runs in reverse and returns energy to the battery instead of throwing it away as heat. It recovers part of what you spent, especially in the city.

V2L

Vehicle-to-Load

The feature that turns your EV into a battery on wheels: an outlet that powers appliances, tools or a campsite from the car's energy. Very common on Chinese models.

Cell-to-pack (CTP / Blade)

A way of building the battery by placing the cells straight into the pack, with no intermediate modules. It gains space and rigidity. BYD's 'Blade' is the best-known example.

Thermal management

The system that keeps the battery in its ideal temperature range. It can be air (passive, simpler) or liquid (active, more effective), and it matters a lot in hot climates.

DTC (fault codes)